I explained it from Martial's side. While for Man United, selling Martial might be the right choice. Martial cannot show their best performance, Man United has the right to look for another young CF in the next transfer window and put him on the transfer list. But it may be not easy to sell Martial if Man United expects high transfer funds. I doubt if Sevilla and Juventus want to spend much money to sign him because Martial maybe planned only as a substitute player, not as a main CF there.

Then, the situation can be the same as in Man United.