I'm sick of people pulling out the "Red Dead Redemption" card whenever a PC release comes up.
Red Dead Redemption was a completely different situation. The code was a complete mess on the PS3/360, they would have had so much trouble trying to port it. It would have been worse than GTA IV. Red Dead Redemption was developed by Rockstar San Diego, and they rarely port their games to the PC. They also didn't expect the game to be a huge success, and shortly after release the team broke up.
A Red Dead Redemption port was doomed from the start, there were so many things holding it back. I'm tried of seeing people complain that they can't fall asleep at night because they don't think GTA V will get a PC release, when Rockstar North has always gotten their games ported to the PC.
They've always brought each GTA title to the PC, why stop now? Especially when this game is going to be a huge success.