Do Whittaker/DDP as a number one contender bout for June/July, Whittaker has been ready to go along with wanting to be active and possibly getting another win under his belt will help generate interest in this bout.
The UFC might avoid that and just do Izzy/DDP since it's a fresh matchup, there's no one else Izzy hasn't beaten yet in the top five and DDP is the highest ranked guy coming off a winstreak. It'll sell well and might be a great headliner for the UFC Africa card they're planning on doing.
I really don't know what to do with Whittaker, just match him with any top ten guy coming off a win at this point to keep him busy since the UFC aren't giving him a title fight next IMO.
If he wins then we'll see what happens, MW is slim pickings right now in terms of who will be the next title contender so it's not out of this realm that he gets another shot.