The Premier League is getting more complicated than we realize because, if you look at Manchester City and Arsenal, they are not doing well, and the only team in the lead right now is not Liverpool. Despite a lot of effort from all clubs, it isn't working out for them, and the only team enjoying the league and winning is Liverpool. I don't even understand why you are bringing up Manchester United; they are even worse than the other teams, and if they weren't fired, at least they would have improved.
Chelsea is even better than Manchester United because, ever since they started the season, things have not been going well, and, with the momentum they have had so far, it is impossible that they won't finish in the top three. And all this club you are mentioning have nothing to offer this season worst is even Manchester United so their is nothing more important than been among the top three.
I don't see complications in the Premier League but a change of era. It will be terrible for Premier League for them to allow Manchester City to win the Premier League for the 5th time. That will clearly send a message that Premier League belongs to Manchester City and it will turn to a farmers league that they used to mock Laliga back then, it will just looks like the table has turn around. If Arsenal is even the one on the top of the table, I will make me happier than any other fans.