It has to be one of the following: Povetkin Helenius Adamek Fury Solis Boystov I wouldn't like to see him fight Adamek or Boystov, nor someone like Chagaev and I don't think Adam Booth would have him go in with someone like Pulev.
Povetkin - This content is protected Helenius - This content is protected Adamek - This content is protected Fury - This content is protected Solis - This content is protected Boytsov - This content is protected
Povetkin - Be a good fight and plausible as Haye could want the title to either go out on or set up one last big fight Helenius - Adamek - Haye wins by brutal KO after one or two punches on that polish glass Fury - Could be a good fight, but Haye doesn't want to fight at "domestic" level anymore so won't happen although I'd like to see it
I love to see Adamek or Solis, but Solis still needs to get in shape though. If it's Povetkin then that's a bonus as well.
I doubt its anyone from that list, I reckon it'll be someone else with a decent WBA ranking, Luis Ortiz looks like a likely candidate. Haye-Adamek in Poland would be fantastic, the banter on ESB will be quality.
If Haye wants to become a mandatory I'm assuming that he's going the rematch with Wlad route. Vitali, if he fights again, won't have more than 1-2 fights left and Arreola-Stiverne is going to become his mandatory so Vitali is probably out. Pulev-Fury/Cunningham is going to be Wlad's IBF mandatory so I don't think Haye goes that route. Povetkin is Wlad's WBA mandatory and they said Wlad-Povetkin has to happen by the end of August. The winner of a Povetkin-Haye fight in JUly won't be fighting Wlad in August. I don't think the WBO has named a mandatory and Haye's rated #4 by them so he could easily fight for a mandatory fight in July. The guys rated above him are Helenius, Banks, and Boystov so I'd guess one of those 3. But the sanctioning bodies make rules up as they go along so who knows.