I'd imagine that the mathematical impossibility of beating Wlad twice in a row would make an immediate rematch, even a lucrative one, very unlikely considering the popularity Povetkin would enjoy, following a victory. He could (and would) sit on those belts and milk them for years, making mandatories travel to Moscow and win decision after decision(controversial and otherwise)...cementing his status as a national hero.
If Povetkin wins then He has to face, Wladimir then Vitali in consecutive rematches x5, If he miracously wins all 10 rematches then he has to face a final 2 on 1 match against Vitali and Wladimir. If he wins the final match, then and only then will he be allowed to keep all the belts.