I'm a bit resigned to the fact that Martial is just not Jose's cup of tea, and he is best off playing under a different manager. Jose would probably put up with Martial if he was as good or delivered as well as Hazard or even a pre-Utd Alexis, but he hasn't, even in his best patches of form. For sure, Jose holds his defensive liabilities against him, which is rather unfair for someone that really is a forward, if not a central striker, but Alexis & Hazard have at least put in better shifts defensively, and have better offensive repertoires.
I'd hate to see him go, but it's definitely more likely than not at this point, so might as well make the best of a tough situation. Would I swap him for Willian? Probably not, unless there is a lot of money coming our way, and even then, I'd be wary as I can definitely see him blossoming under the right system, and rubbing Jose's nose into it to boot. Definitely would rather see him go abroad, if at all possible.