Bro, this question you just ask shows that the problem of Manchester united is way beyond coaches or managers.
It's very true that Eric ten hang is a very good coach and he has proven himself already at Manchester united that he is a winner, because even in the mids of all this turbulence years as manager of Manchester united, he still manage to win something at the end of the season, so that shows what he is made of.

 let's look at the previous managers that has coach Manchester united, they are all top quality coaches, from jose Mourinho, ole gunnar solskjaer and luis van gaal, but due to how the club is being structured, they all fail to win the premier league, and and if you look at what Ronaldo said about Manchester united, it was the actual fact, nothing has changed, it's more of a commercial club than a football club, just as Luis van gaal rightfully said, so in my own perspective, nothing at Manchester united is going to change regardless of if ten hang is being sack or not, untill the way the club is being structured is addressed.
So changing of manager wouldn't change anything about this Manchester united side, until the real problem is addressed.