The question though would be, why would they do that, if that's the reason for the later release? I understand it if they are doing this at the start of the console generation, but thinking about it further, Rockstar is only one of the few developers nowadays who keep practise that outdated business strategy.
The reason as always is to shift consoles. We are coming to the end of this "generation" so the more you can do to shift this old generation of consoles the better. It is no secret that Rockstar had some sort of marketing deal with Sony. It is also no secret that Sony had a GTA 5 bundle. As far as I am aware in the UK the PS3 GTA 5 bundle was the cheapest way for non-console owners to play GTA 5 (£199).
Whilst I am not convinced that "keeping it off the PC" was a major part of any Sony deal, I can see it being an "extra" thing Rockstar offered Sony to sweeten the terms of the Marketing deal.
It isn't just about selling consoles though it is about exposing PC gamers to Sonys "Eco system". Getting people invested in the PS3 means they may move up to the PS4 when it is released. Meanwhile Rockstar know that holding the PC version back for several months will not have a huge impact on the number sold on the PC.
I have a feeling, that the money from sony/ms for holding back the pc version includes more this time.
Maybe shortly after the release of the current-gen consoles (Xbox None/Paystation 4) GTA V will be released for just these consoles.
It will be the killer game for these; finally the console player can see by themselves, how a game look on what pc gamers call "medium settings".
Then, later next year, when the console sales went down, they can finally release the high res version.
There are really no other reasons, why c* hold it back.