Yes, I think you're pretty much spot on. The problem we have, though, is even some of this "new core" are not exactly proving themselves indispensable either. Digne and Richarlison - who were surely two of the key players that the club intended to build around - have not stepped up this season at all (injuries being one reason). James, our one technically brilliant player, is fragile. Doucoure has done enough to persevere with, but Allan really hasn't. He's not been on the pitch enough to make himself central to what we do. Godfrey has been versatile, but needs to pin down a specialised position and stake his claim. DCL has fallen away and the doubts about his full potential are now resurfacing. Mina is probably the leader at the back, but he's also in and out. In other words, even the players we think we'd like to keep are not really proving to be reliably effective.
That said, there should be no way back for Gomes, Iwobi, Sigurdsson, and Davies. All need to be replaced. Holgate is hardly worth keeping either and time is up for Coleman. If the new core were reliable, we could be more charitable and patient with some of the younger squad members, but I'm not sure the likes of Holgate and Davies will ever amount to much in our environment. The results in 2021 will help Carlo's case for new signings as the scales will have dropped from eyes about what we really have about us.