The winner is obligated to face the WBO and IBF mandatory, it's already a given that the winner will dump the WBO (Haymon doesn't deal with them regardless) allowing Uysk to fight for the vacant title in February. Whoever wins has to face Pulev (IBF) next or dump that too.

Joshua can't be frozen out as Hearn will have the WBO title regardless and all the top heavyweights... barring Wilder, Fury and Ruiz of course. However, should Joshua lose he's going to need a year or so to ease back regardless.