I'll explain logically why GTA has a very little chance of getting on the Wii.
Firstly, the amount of memory needed for the advanced RAGE engine GTA IV uses wouldn't work on Wii. The PS3 version is using the cache from it's hard drive to constantly keep GTA IV running without a framerate drop - the Wii can't do this because of a lack of a HDD.
Also, HD visuals is what brings GTA IV to the front, but since the Wii hasn't got enough power, IV is a no-no on Wii.
Besides, the backlash Manhunt 2 got and the mediocre sales of Table Tennis on Wii indicates that the relationship between R* and Nintendo is rocky.
Don't hope on GTA on Wii.