In general, yes, because he is a very good receiver. But I would certainly keep an open mind about trading him if he could net, say, a second round pick. Otherwise, keep him and hope for a healthy QB and OL and watch the three-headed monster at receiver feast next year.
Another big thing is, what will Gallup's market in FA be in a year? If it's 12-15 mil/yr I'd rather keep Cooper, who is a true #1 receiver and not retain Gallup long-term. If it's 8-10 mil/yr then moving Cooper and signing Gallup becomes more attractive...