I've mentioned our lack of options on wing as a reason to keep Coutinho but another possibly more important reason to keep him is because he's one of the few players in our squad who can help us unlock defences when teams park the bus.
Despite the positive result against Palace we had trouble breaking their defence down. This is where having Coutinho might help. Our midfield is great when the game is more open and especially if we're counter attacking, but they look very subdued against teams who don't want play.
Again, unless we get a perfect replacement, which we probably can't, don't sell the cunt.