If they can take corrections from the mistake they made this season and making improvements of their performance they fit be the best team next coming season that means if they make a concrete arrangement. Because this season didn't fevor Manchester United and the Chelsea at all is like the Chelsea performance was even get better than the Man united even though they where also not good though the season they perform admirable against some of their opponents.
In fact, the performance of these two teams was very complex and at the end of the season both of them were pushing each other to finish in a better place. I think Chelsea beat Manchester United yesterday by finishing above them and securing a place in the conference league, but what we saw from Manchester United after winning the FA Cup made them get a place in the European league.
It is clear that in the end Manchester United could reverse Chelsea's previous situation and even though they finished below Chelsea, they won the title and also had slightly better European competition. I think both teams should recover next season and regarding the polemic about changing coaches between the two, it will definitely take a long time to build everything from scratch.