Yeah, that would really be a BIG benefit for flexebility, well I doesn't have to be 4.5gb, imagine if the scripters can just start with a empty map, and then download ressources to add cars, skins etc, the modified "game" wouldn't be that big, don't you think? I mean, as it would be just a platform (at the beginning) for developping gamemodes, it doesn't need the original SA map, but ofcourse, you could download a ressource to have it, same for cars, weapons, if you want the ones from the original game . I think we can get the best out GTA SA, to me it's the best platform to build an online dev platform for any kind of gamemode: Stunt, Roleplay, Deathmatch... Everyone would be really happy to have such a platform but well, it's just a suggestion, I don't know if MTA devs are still fully into MTA SA development, I really hope so, and I think it could really make people pay more attention to our prefered SA Online mod!
EDIT: I'm pretty sure the MTA team can do that, let's just hope they aren't planning to develop a mod on GTA IV, this would be such a waste of time to me, this would take years till Rockstar gives their source code, and I don't think they'd ever give them anything because of the new platform they got. Let's just finish things that been started on GTA SA, and as I said before, it's certainly the best base for building this kind of online gamemode dev platform.