Regardless of how "extremely likely" it may be, a PC version does not currently exist, therefore, there is no platform for Rockstar to port over to the next generation systems that will be any different from the current gen whatsoever.
That is not quite correct. First of all, the way you worded it sounds like you know what Rockstar planned, which you clearly don't. Neither do I, that's true, but there are so many indications for a PC release of GTAV like with no Rockstar title in the past. I am talking about the files you can find in both console versions of the game. In the visualsettings file, for instance, there are things like Bokeh DoF mentioned, which is a DirectX11-exclusive feature; and current-generation console do not support DX11, they are running on a mix between DirectX9 and 10 (Xbox 360) or PSGL, LibGCM, et cetera (PlayStation 3). Another thing that has to be considered is the fact that there is a mile long bug report file in the PS3 version of V. I suggest you to take a look at it: http://tny.cz/70a52275 And in case you've doubt about the existence of this file, you should insert the disc of V into the drive of your PC, and look for the file yourself. Various members of the forum confirmed that the file does in fact exist, so it's not a fake.
You will probably ask what's so special about a simple bug report file. Well, the fact that PC is mentioned hundreds of times, starting in June 2012. I've been looking through all the data for a bit a couple of months ago, so did many other members of this forum, and the things you can see there are quite interesting. It shows that V has been developed for PC alongside the console version, just that it started a few years after the development of the PS3- and X360 versions started.
So, by that logic, it's not only that V exists for PC, but the game isn't exactly a "port" as it has been developed simultaneously with the console versions; which doesn't mean the release is also simultaneously, though, as you can see. There can be two reasons for the delay, or possibly even more. One would be that Rockstar hasn't finished the development of the PC version yet, either because there is/was some trouble or because it was planned so. The other reason would be that they got paid to push back the PC version. Who would pay money for that, though? I could only think of Microsoft and/or Sony, as they are the console manufacturers and they're benefiting from the extra sales through the platform exclusivity.
They're not trying to avoid making more money, quite the opposite in fact, they're trying to make as much as they can while risking as little as humanly possible. What are they risking I hear you ask? Three things, the first of which is a potential investors trust that may or may not want GTA V to remain a current generation exclusive for the following two reasons.
GTA Online may be harder to port than any of us understand, the intricacies behind a system of its size, scope and scale are unknown to most, but I'm willing to bet that getting it running on another platform, is going to be a pretty tricky and require a very big investment, both in terms of money and time. This leads me on to my final reason, the time and money it'd take to completely shift GTA V and GTA O onto another platform might be too expensive for the profits to be anything significant.
Popularity fades with time, the more time we go without a PC version, the less popular GTA V becomes, the less profitable shifting it onto not one, not two, but three different platforms along with its MMO-esque online mode becomes. Just because something appears profitable on the surface, doesn't mean that it will be in the long run, and to many TT investors, it might seem like a better idea to put money towards developing the next GTA game along with other Rockstar titles, then bother shifting GTA V onto a new platform for less than half of the potential income it got when it initially released.
To avoid making a loss, the total sales would have to be good enough to cover the development costs. That doesn't automatically make the product profitable and worth the time that has been put into it, though. It's only then profitable when the sales go way beyond covering the development costs. And that certainly would be the case with GTAV, given how popular the game is. It isn't the first time Rockstar delays a game for a particular platform. In fact, the vast majority of their games were delayed for the PC in the past. If you consider all the titles that got released since GTA III in 2001, then you will see that every game which eventually arrived for PC got released for the platform about 5 to 8 montha after the console release. The announcement always happened between one month prior (GTA San Andreas) and five months after console release. The one and only exception is Bully, but that was because the PC version was a port of the Xbox 360 version, which in turn released over one and a half years after the PS2 version.
Honestly though, I have no idea why you're counting it as a problem that the PC release happens months after the console release. Rockstar does it every single time and Max Payne 3 is the only exception after many years. It has been almost three months since V launched for the PS3 and X360. The PC version could be announced any week from now. Or maybe, PC gamers aren't lucky enough and it won't happen until early next year. We will see.
The problem is there's simply not as much monetary gain in porting something of that size and and scale as you might think. First we've got to calculate how many people on the previous generation own GTA V, I seem to remember that being somewhere around the thirty million mark, now the next generation consoles have about ten or so million users, the PC market I'd wager has a similar number so even if it were to sell across the board on day one with no discount it'd still fall short of the game's previous sales by a wide margin.
A good estimate would be that maybe four to five million people decide to re-purchase GTA V and another three to four million pour in slowly on the PC side (thanks to Steam sales, et cetera, this could take place over a number of years so the overall major profit may not be visible at any one time). So we're talking maximum sales over the next few years of perhaps 10 to fifteen million copies. While that is a lot, another GTA game on the next gen sure would be easier to make, more profitable and take up less of Rockstar's development time.
I think you see it completely wrong, not to mention that there are some factual inaccuracies. I'm not sure how large the userbase of the next-gen consoles is so far, but you may be right with the 10 million users. However, you're way off with the userbase of the PC market, because it's much larger than that. First, you have to consider that there is Steam, and Valve has recently announced that it has over 65 million users. As far as I know, Steam makes about 75-80% of the PC market, so if you count the retail market and other digital platforms as well, there are presumably over 75 million potential customers. Sure, not all of them are interested in V or the GTA series in general, but you can say the same about every platform that exists. As of October 30th, Take-Two sold 29 million copies of V world-wide, but, well, there are over 150 million current-gen consoles out there.
Also, no offence, but you have to be utterly insane to think that creating an entirely new game is easier than porting an already existing title to three another platforms. The thing is that porting games does not require that much work as you make it sound like. Rockstar has already plenty of experience with developing PC games, as evidenced by Max Payne 3. The fact that they are able to develope a game for PC from scratch shows that they have gained knowledge about the x86-architecture over the years, you know, the architecture the PC, PS4 and Xbone share. The only differences between all these platforms is the way the RAM works. Both next-gen consoles have unified RAM that is shared between the system and the GPU, whereas PC uses DDR2/DDR3 RAM for the system and DDR3/GDDR4/GDDR5 [V]RAM for the GPU. Porting games between these three platforms is no work compared to porting a game from a PS3 to PC, or creating a new title for platforms you haven't worked with yet (though, it's like developing a game for PC; and Rockstar did it the right way with MP3). Oh, and another thing...
You’ve talked about time-to-triangle [the time it takes a developer to create the base for a game that matches the hardware’s graphical power] and how it can lead to amazing experiences from indie developers. What about the major publishers that are known for producing the same kind of content again and again?
Anecdotally for the indie titles I’ve been hearing 4 weeks to bring a game from PC to the PS4, which is quite fast. For some of the AAA titles I’ve been hearing 2 months, which is also quite fast, and that has really helped us in creating that strong launch line-up.
GTA Online won't only be hard to port, it'll be an on-going port that will probably last months if not years at the very least, and costs of keeping those servers running and those technicians employed isn't cheap, in case you've forgotten Rockstar likes to cull a fair few of the staff after it completes a major project like GTA V and then starts rehiring when the next large project comes into town like Red Dead or Max Payne. To put it simply, this is going to cost them a lot over a long period of time for very little profit.
But, on the other hand, you have to consider that they will eventually have to port GTA Online over to the next-generation systems. It's called "GTA Online" for a reason, and not "GTAV Online". It's because future GTA games will also be incorporated with the new multiplayer. You decide what's more likely; they wait for a few years and don't release V for any more platforms, because porting GTA:O to PS4/Xbone/PC would be too much of a hassle and it's better if they wait for their next title; or they're porting GTA:O together with V on three more platforms now and already know how it works when they are about to release their next game.
I understand it if you think there won't be a next-gen version of V. But, I do not understand why anyone would think they won't release this game for PC. Especially if there's already a ton of references to it in the console files.