They already made a GTA clone, it was called Body Harvest! Heh heh, okay, so the games are a quite bit different, but it did at least have the car-jacking theme...and airplane jacking and boat jacking. Actually, Body Harvest and Space Station Sililcon Valley were both made for the N64 by DMA before it became part of Rockstar, and I thought they were awesome games (albeit a little flawed). I'd love to see a new game from them! But I would bet that a port of some PS2 game is more likely.