Firstly the on-loan players inwards will almost certainly leave - So Coady and Vinagre. While we might try keep Coady on, I'm guessing he'll prefer to head back to Wolves, and take his chances there, rather than face in to an uncertain year in the championship.
Likewise all the players out of contract will all leave, either because we can't afford them or they have better opportunities elsewhere. So Seamus, Tom Davies, Mina, Doucoure, Townsend will likely all leave.
After that, its all guesswork of what players teams might be willing to pay for. Pickford has value, and will likely want to leave to keep his England spot, but I don't see any top 6 club wanting him, and if there was much interest in him, he likely wouldnt have just signed a long term deal. Patterson and Godfrey might have some interested clubs based on their relative youth and speed. Iwobi might have some interested clubs, but he may prefer to hang on for another year to be able to move for free in a years time instead. Onana will probably want to leave and we'll likely make a profit on him, but not by all that much. Grey too would be similar, he's got skills, but he's not consistent enough showing it, so again a profit, but not something dramatic. I don't see anyone taking a chance on DCL, his days as a PL striker seem very numbered unless he has a dramatic recovery before the end of the season. While we'd love to sell Maupay, I can't see anyone paying money for him, I'd think we're just stuck with him until his contract expires, unless we maybe get him some loan deals instead.
The rest, we keep unless we get a decent unexpected offer. Maybe some of Tark, Keane, Holgate, Garner, and McNeil might have interest, but I think most likely stay.
TLDR: Its grim grim stuff. Unless some of the youth team players can step up to an unlikely level, its going to be a rough year.