When the Klits do retire, it will be good for boxing! Every promoter with a heavy wants the Klits out of there, they're like a pack of wolves surrounding the Klits waiting, waiting and waiting. I think they will be waiting for awhile longer. Vitali will go first, which will open things up a little.
Nobody knows when Wlad might step down, probably not until the whole thing starts to bore him, there is no one to challenge him anytime soon, in my opinion.
I don't think there is a way to predict who might be the next champion, not until Wlad announces his retirement, which could be a few years from now. It's going to be a real interesting time when that happens.