I don't see any way that the Wizards give up John Wall for that type of trade package.
I do think the Kings could move Cousins but probably not to Washington. This is a weak draft class plus Washington would have a very good chance at being a playoff team next year with Cousins added to the mix so that pick's value isn't overly high either.
If Sacramento do move Cousins, I think it would be for a player already in the NBA. Either a talented youngster still on his rookie contract or a young veteran who is already at All-Star level (something like LaMarcus Aldridge).