So far (i repeat, 'so far'), nothing has been shown for GTA4 that was not possible on the ps2 (judging from its similarity so far to san andreas, imo)
So i don't see why a (if not GTA4, another) GTA game could not be brought onto wii without any difficulties..
Personally i hope they just bring GTA4 to PC, because that has always been my favourite 'console' to play it on, which could change if they do a wii version correctly







