When Zaha is on form he is an excellent player and difficult to do anything with. He has had a poor season and I think a lot of that is contrived between agent and player to make sure he does get his move this summer.
If we were in a situation where money wasn't a concern then yes I would sign him for the short term impact he would make... but , we don't have money like that to risk on a player who will have little or no resale value in maybe three years.
If, Crystal Palace happened to be interested in some of our players like Iwobi, Tosun, Walcott ,Sigurdsson or maybe Bernard then just maybe something might happen..... that is if CA has any interest in the first place, but, I think it is so unlikely that it just isn't worth considering at present.