He hasn't downed tools but he's playing like he knows he's off in the summer. He has always been doubled up on, sometimes with a third as cover and in seasons past that hasn't mattered because he will have generally managed to put a consequently free Palace player in. Zaha is looking poorer this season because (for me) Palace are poorer, with other players not making the best of his undoubted skills. Also, he plays better with another wide player, Bolasie initially, and latterly Andros Townsend, who has been injured for some time. Their presence would bring the best out of him.
Not sure his expectations of a move (or ours!) are going to come to fruition. I expect to see him in Spain / Italy / Germany next season.