Its going to be a European title challenge so I would have though it has to be someone in their rankings. http://media.wix.com/ugd/dd6960_be80a281f3f54baaa52761aa08a8b08f.pdf
Looking at this the best credible opponent that doesn't appear to offer a huge risk is Arthur Szpilka. He just beat Adamek and has only 1 defeat, to Klitschko's next opponent Bryant Jennings. He also has a decent KO ratio on paper but it has mostly been vs cans. So it ticks a lot of boxes and if Fury can do a better job on him than Jennings did that will help build the Klitschko fight.
How in the hell can a promoter put tickets on sale with no opponents for the home town heroes?The public should be protected from these type of promotions.:-(