I see Tiger as a really good player like a lot of other really good players, so I think he can win again, and maybe a major. But so what? Tiger has always been about 19 majors, nothing less. If he can't win 5, or at least 4 it's meaningless. Sure, it's a nice comeback story, but he'll still leave golf with a big old "What if?".
Because Tiger never really opens up in interviews it's hard to say what he wants out of this comeback. Personally I think he's really trying to see if he can get it back and win 5 more majors. It may sound ludicrous to us, but I see that as what's driving him. I just can't see Tiger putting in all this work to be #9 in the world and win a tournament or two, even if one's a major. It doesn't fit his personality, imo.
The only other thing I could see is it's all about the money. He knows he needs to play and play pretty well to keep his brand going. And if youy're going to say "He already has more money than he'll ever need" you just don't understand rich people.