Whoever the coach is, Manchester United won't change much in my opinion. You can look at their list of coaches so far and find out who has helped Manchester United win the title the most, I think it's none other than Sir Alex.
It would take a lot of time or a truly genius coach to get Manchester United back to their prime of almost a decade ago because it would be very difficult with their current state of internal turmoil and against ultimately more solid coaches like Pep and Arteta that Manchester United look much smaller at the moment.
They must be aware that by keeping Ten Hag on this season, the most likely outcome is that their performance could be the same as before and they must know that this will be the reality especially with their not-so-smooth start to the season.
But when replacing, in the end it will always be the same as this when their squad officials only make Manchester United a cash cow although now the Glazer Family's ambition in business can be slightly dampened by Sir Jim Ratcliffe.