Wii U and PC versions of Grand Theft Auto V not off the table
While it appears that Rockstar have only committed themselves to releasing Grand Theft Auto V on the PS3 and Xbox 360 at the moment they haven't ruled out releasing on other formats.
Rockstar's Dan Houser stated that they are still considering doing versions of the Wii U and the PC at the very least.
Houser said, "Everything else is up for consideration. That's all I can give you. The main thing is we are notwe are a third-party publisher. We're not Nintendo, we're not Sony, we're not Microsoft. We love all of them in different ways. But we can do what we want wherever there's the appropriate business opportunity and chance to find a market. If thats on Apple we put something on Apple. Wherever it might be. I think that's the fun in what we do. We see ourselves as a content company that uses technology. We don't make it; we use it to make the most fun stuff."
A PC version is almost definitely assured given that the series was born on that format and every GTA game has seen a release on PC albeit a bit later on from the console release for later games.