I think he needs to work his way into the no. 1 position the same way Wladimir did. With that I present the following list of fighters he must face and defeat before getting a shot at Wladimir again. Start with Lamon Brewster, followed by Toney Thompson, followed by Chris Arreola, followed by Sultan Ibragimov, Followed by Povetkin and finally Dimitrenko. Only after he defeats each and every man listed here would I consider him worthy of fighting the champion for a belt.
No one has to defeat that many contenders to get a mandatory position. I think beating Povetkin would be enough to get him in mandatory position.
I'm not sure Haye could beat Lamon Brewster. He's only chance would be to out-box him and that's quite a task for someone who's about the same height as Brewster.