I think he'll keep it as long as he can, meaning more catchweights and everything. I mean I'm pretty ok with it. Problem will be if the WBC gives a mandatory and he refuses but I think the WBC is happy with Cotto as a world champ and will work with him.
He should be stripped and the boxing universe should strip him of the lineal title. Knowing that the MW lineal title is going to be on the line between 2 junior middleweights at 155 and the real middleweights can't get near it is a joke. Now there's practically a stone between 2 lineal belts in consecutive weight classes.
He will never have to vacate, because for as long as he holds the title, he won't be forced to take a fight he doesn't want. :smoke