Chris Arreola could very well be the man to put Wlad down, he's everything that gives Klitschko problems in the ring: relentless, aggressive, iron-chinned, heavy handed, and deceptively quick. Give him a year or two, and Arreola will be on top. He just beat another top prospect named Chazz Witherspoon, and it's rumored he'll fight the shell of David Tua next.
Also keep an eye on Alexander Povetkin, who's actually Klitschko's IBF mandatory. He's almost like a bigger, more technical version of Juan Diaz. He's another guy who applies pressure, but his hand speed and combinations are the most impressive thing about him. He doesn't have the biggest punch around, but it's enough to command respect.
Of course, we can't forget about David Haye. If the guy brings his power from cruiserweight up with him, he'll be a very dangerous and exciting heavyweight. Not only that, but he's got the personality to make himself into a legitimate star. Only thing is that his chin is a bit questionable, but that could possibly be because he's been killing himself to make 200. He's got a ton of speed, he's got a killer instinct, and his jab is a very good weapon.
Povetkin and Haye, though, are a bit on the smaller side, while Arreola's got the size to hang with anyone. All three of them have crowd-pleasing styles, so you're gonna get a good fight if any one of them is involved, especially Arreola, who pretty much fights like a Mexican ('cause he is....Mexican American).
Basically, don't sleep on the heavyweight division just yet. Between these three, the potential that Samuel Peter and Ruslan Chagaev have, and other young heavyweights like Witherspoon, Eddie Chambers, and Kevin Johnson, all is not bleak amongst the big men.
__________________ Israel Vazquez....Super Bantamweight Champ....Super Heavyweight Heart
This man is my hero.