There will be a clear out, and not just because the club may wish to "cash in" some of their (depreciating) assets.
As frequently happens with relegated teams, the teams in question sell players, or, are compelled to sell players - or, players are poached, or head-hunted, or, simply want to move somewhere else where better opportunities lie..
Just this morning, I have read that Garnacho (by no means United's worst player) has, according to the Guardian, put his future at United "in doubt".
Another article quotes the captain, Fernandes, (also by no means United's worst player), rather gnomically, offering the following thoughts while simultaneously stressing his strong support of the manager ("He's the right man"):
“I have always been honest. I’ve always said I will be here until the club says to me that it’s time to go. I’m eager to do more, to be able to bring the club to the great days. In the day that the club thinks that I’m too much or it’s time to part ways, football is like this, you never know it. But I’ve always said it and I keep my word in the same way.
“If the club thinks it’s time to part ways because they want to do some cashing in or whatever, it’s what it is and football sometimes is like this. The players have said that this season has been unacceptable.”
Now, as is all too often the case with relegated teams, once the core competition (in this instance, the Europa Cup Final, not the last day of the Premier League) has concluded, players may choose to place themselves in the shop window and signal their desire for departure - which is what I think is happening here, and it is no coincidence that this is taking place this morning, the very first - even morning - following their defeat at the Europa Cup Final, and before the opening of the ,transfer window.