Firstly, I wasn't aware that any features of GTA4 were official. Secondly, we have no idea when it will be released and it could be 2 or 3 years from now. With the release of Blue, modding will be possible and there should be plenty of popular mods by that time. Thirdly, no-one can really speculate what the MTA team will do. They will most certainly not go with Driver 3 because that will be as old as the GTA games but with significantly less demand, thus they'd be better off staying with GTA.