Soon we will reach that uncomfortable point of realizing that even if he didn't die in 96, he would have died of other causes since then. Or, in the best case scenario, he would be a grandpa.
If he's still alive, while it would be extremely interesting to find out and hear about what he's been up to, I don't think there's anyone that could still have any reasons to believe that he is alive at this point.
There's way too much that we know about his death, his relatives and friends (many of them now dead too). We've seen too many sources and official documents, had people meet friends of his friends and family, and there is too much technology and information sharing for anyone to go unnoticed anywhere in the world. Not to mention the potential financial gain from exposing such secret preventing anyone who's ever seen 2pac from not going public with it. And there's too many people who were deeply involved in his life, including really close ones, who would surely act one way or another, leading to exposing him. On top of that, he would hardly have any reasons to hide anymore. Yeah, I just don't think even the most die-hard conspiracy theorist could come up with a reasonable counter-argument these days.