To be honest, I don't think many do because of WWE's booking. They don't commit to pushes when it comes to young talent.
Everybody's a young talent at some point in their career. They don't have to be committed to any of them for great lengths of time; small bursts of attention will do the trick in the long term. A "bright future" in today's WWE is like...getting a match on a PPV and not jobbing to Vince's flavor of the month.
Ryback, if they don't lose interest and prematurely pull this gimmick out from under him, will be successful. They're never going to make another Goldberg - not for lack of potential, but simply because it's been done and people don't typically like to get behind the same thing twice. But it's been said in this thread already, I could watch Ryback destroy jobbers for months before it would get boring. The slow-and-steady approach is definitely the way to go, but the amount of A.D.D. in Creative doesn't work towards his advantage.
Brodus Clay...no. I'm not a hater, but I'm also not a huge fan. He's a pure comedy gimmick, but the more they walk that line the more I lose interest. I give it through the end of the summer and he's back to square one.
Antonio Cesaro has a fair shot at the big time, but I know a whole lot more about Claudio than his barely relevant WWE alter-ego. I just want to see MORE of him, that's all. My intuition says he's going to be big, but we've seen better talents come and go on flukes or lost momentum. Hell, I was on the Alberto del Rio bandwagon last year, and I was just as disappointed as the lot of you that he turned out to be a flop (ok...I think he's a flop).
I'm not seeing it with Sandow, but I honestly don't watch Smackdown on a regular basis. So I can't really provide any sort of legitimate analysis on him.