They had better keep Zaniolo. 
Because Zaniolo is a crucial player for them even though he has a serious injury history. He is very young now and he has long years ahead of him to develop his performance more and more. If Roma lose him now I don't know if they can find a player who is at least as good as Zaniolo.
Indeed. They should keep Zaniolo since they have no other good right-wingers. Mourinho will be difficult to look for his replacement if Zaniolo moves to another club. No doubt his role is crucial in AS Roma squad, Zaniolo is also a promising player to develop his value in the future. AS Roma must think to keep him on the squad, so I am not sure if Zaniolo will consider leaving, except he has a bad relationship with Mourinho. Till now, I never heard any rumor about his bad situation in AS Roma. Because Zaniolo is a crucial player for them even though he has a serious injury history. He is very young now and he has long years ahead of him to develop his performance more and more. If Roma lose him now I don't know if they can find a player who is at least as good as Zaniolo.