Khan's whole game has been based on his speed. There is not a lot going on upstairs with him and his speed has been used to fluster his opponents. He does not see punches well and is not a thinker,getting the changes Hunter wants on automatic where he can perform them at his warp speed is a big ask and Khan is hard wired to do what he does already.
Under pressure he will resort to his main asset which is speed and the old habits will take over and the new stuff will go out the window.Making changes in habits on a deep level where it is second nature is actually more difficult when the student is super fast because everything is happening so fast where you can't monitor what you are doing especially when you have grooved in old bad habits. I don't think you can teach him too many new tricks just work round what he has got already which is what Roach did.
If he is to change which I don't think he is capable of he has to be with Hunter all the time. But he could actually get worse as right now he is very competent at his technical incompetence and that may be more dangerous to an opponent than Khan not being confident and competent performing technical competence.
IMO we have seen the high water mark of Khan and he will never really be considered as a force or threat to the top guys. I just don't see him getting better and just see more and more talk, a series of fights against lower level guys and then him getting battered when he steps up and then more and more excuses and Mayweather fight talk. That seems the pattern to me.