Its always tough to tell with the E. If you go back a few years, it would have been a safe bet that Shelton Benjamin was going to be a superstar, but instead he's stuck as a midcard talent putting young guys over. At the same time, I don't know that too many really expected Punk to become a mult-time world champion when he moved from ROH to the WWE (well, OVW).
Miz - just can't see him being a top guy, for some reason. A poor man's Chris Jericho eventually.
Jack Swagger - a guy who definitely has tons of potential in the ring, and he's getting better on the mic. Could suffer a similar fate to Benjamin if he doesn't continue to develop. Really wish the E would give him a manager.
John Morrison - a future world champion. I'm still not convinced entirely that he's great in the ring, but he connects with the fans well enough. A less talented version of Shawn Michaels.
Cody Rhodes - I'm not entirely sure. For a long time, I figured DiBiase had more upside. Now I'm not certain anymore.
Teddy Jr. - has a slightly better look than Rhodes, which I think could make the difference. He might get pushed to the top, but I see him more as a long-term fringe main eventer than a true steady one.
Kofi -losing the accent and changing up the gimmick a bit made a world of difference. He finally has some character and that's key. The feud with Orton could make Kofi. Potentially a top guy.
Sheamus O'Shaunnessy - generic in some ways, but the "big Irish brawler" is always going to be enough of a gimmick.
Dolph Ziggler - just can't see him connecting to the fans enough or generating enough heat to overcome his size issue.
Drew McIntyre - big, with a decent look and not bad on the mic, so he has potential. Haven't seen enough of him in the ring to really be convinced, but he doesn't suck and that might be enough.
Tyson Kidd - DH Smith had some upside, but I think Kidd is always going to be limited by his small size and he has yet to show any real personality. Tough to gauge.