I don't think Southampton's squad is good enough now to win the Championship, or get in the Auto Promotion spots, and it's probably going to get a lot worse for them.
Leed's are one or two players (who they will lose) away from being below that level too, and even more so if Bamford keeps getting injured (which he probably will).
My main fear is Leicester, they will lose a fair few players but they're the only real team who came down who really under performed. I think they will manage to convince a few to stay, and they will probably bounce straight back up.
Tielemans will be off, and Maddison will probably want to go to keep his England hopes alive (and he's out of contract next year), can see him going to someone like Newcastle or Villa. They might be able to keep Barnes and Soyuncu, and obvisouly Vardy will stay.