Fury will need a warm up fight or two, been out of the ring for way too long. The most logical thing to do with the fight from both sides is have Joshua fight an American heavyweight in the States and then have Wilder fight Whyte at the 02, then Joshua and Wilder have a mega fight at the end of 2018. Though I think that's a bit dangerous for Wilder and personally see Whyte beating him, so he probably just wants to fight Joshua first and then take everything after that.
Joshua would want to fight Whyte in an all British heavyweight unification fight as it'd make history, plus I don't think Joshua actually rates Wilder that much and looking at what Molina and Ortiz did to him, I think AJ will win that comfortably. But Wilder isn't accepting anything other than Joshua and whilst his team haven't made any offers yet, it'll come down to those two I think. But if Wilder wants more money out of it which I think may have been an issue (I believe Wilder has made something like $2m from a single fight whereas AJ is getting £15m+ for each now) then the only way he'll get that is by fighting Whyte and building his reputation. Heavyweight boxing is dominated by Britain now and the money is all over here, and I think most British fans din't rate Wilder that much compared to AJ, so he'd need a big performance against someone like Whyte to improve his split of the AJ fight.
What heavyweight boxing really needs is AJ to come through Wilder, unify the entire division and then have what would be the biggest fight in years against Tyson Fury.