Well, Povotkin would be the next logical stop but I feel that what will determines his next move might well be the issue of Vitali-Adamek: The brothers plan was that they should hold all the belts together and then, Wladimir should be the next Unified hW. Would Vitali lose against Adamek, it would be Adamek-Wlad and would Vitali wins... I guess that then Vitali will retire (as he told once) and that Wlad would make the necessary fights to put his hold on the missing belt. I guess it would play something along those lines.