By staying in Germany, and fighting carefully chosen past their prime, or journeyman oponents, the Klitchko's have killed heavyweight boxing as a spectacle for the span of the current millenium. They are paper champions.
That is not to say they are without skill, but they have strolled unchallenged for so long that they are effectively 'ring rusty', and in no way prepared, nor equipped, to deal with the mobility, speed, and power of Haye.
As with any contest, there are no certainties, but I have a no doubt that Haye will finish Wlad in under 5 rounds, providing he doesnt make sloppy mistakes. If he fights like he did against Valuev, then Klitchko will have absolutely no asnwer to him.