There have been some attempts at a Red Alert mod as far as I'm aware, but no proper Tiberium universe stuff. Could be interesting definitely, and probably not even too hard to pull off, the first game at least. Just rename one of the existing resources Tiberium and add it to suitable regions, set the scenario to begin in ~2010 or whatever with modern borders, maybe give Kane, Seth, Sheppard and what have you some unique minister personalities and you already have a bare-bones mod.