I think he's a spent force now sadly. Ever since the Eva Caniero incident, he has lost a lot of respect in the game from fans to even players and fellow managers plus his style of football is dated and easily exploited now. I don't think he's happy at United and I don't think anyone else is at the club either plus the fans seem pretty bored with his football. The way he treats players like Luke Shaw is also disrespectful and pretty disgusting. The likes of Klopp and Guardiola who are excellent man-managers are much more likable and entertaining characters who play scintillating football whereas Mourinho is more desperate than Cheryl Cole to stay in the limelight.
If you also said a few years ago that United would be losing to teams like Burnley, Bournemouth, Brighton, Huddersfield and relegated WBA, it would seem like an unreal statement. I think it would be best for all parties if everyone moves on because nobody seems to be happy at Old Trafford now.