Some Pitchers coming off TJ surgeries get even better. Look at Julio Urias. All I know is what they have been saying in reports here and there regarding Sale's recovery which sounds very encouraging. Regarding his approach, unlike other pitchers who have only one pitch to put batters out, he can use any pitch of his repertory to do so. If he comes back 100% healthy, his velo won't be an issue, and if so, in the worst case scenario, he can reinvent himself using more often his slider which is nasty and inducing more movement to his FB. Remember, we also have Bloom's pitching crew in order to help him.
Said that, he is not that old. He can pitch at great level the next 3-4 years if he comes back 100% healthy.