So what hint made you think a PC version would be announced yesterday, 17 September?
1. Sudden sale of a GTA IV + San Andreas bundle named "Marketing app" in the Steam database.
2. 3 months since the game's release on consoles, yes.
4. It would've been part of one of Rockstar's patterns.
5. It was also a Tuesday. Things happen on Tuesdays for a lot of developers.