Parokki on 05 August 2007
The reason GTA and many other franchises were Sony exclusives was not corporate loyalty (just typing those two words together makes me laugh), but the huge install base of the first two Playstations. Going PS exclusive at this point would be an incredibly bad move for any developer. Quite a few have remained that way, and may for the rest of the gen for all I know, but I frankly can't see any notable developers commiting themselves too strongly for Sony at this point. Maybe in a year or so if the PS3 starts beating Gamecube sales levels, but definitely not now.
