That's only seven players! However, I get your drift and don't disagree with your keepers.Hardly any of them.
I would keep Mainoo, Amad Diallo, Ugarte, Yoro, De Ligt and Collyer. Fernandes I'm on the fence, his performances are getting more infrequent. He had good games versus Liverpool and Arsenal but before then, hasn't been up to much.
I don't think defence is that bad - we maybe dont have a van Dyke or a Gabriel but Maguire, DeLigt, Martinez are not bad players. For sure we are short in midfield, wingback and up front. Chido Obi Martin will get squad time this season - the boy is immense. Kukonki also has physicality to step in for minutes but the rest of the u-21s don't look developed enough to easily bolster the squad for how Amorim want's to play. Jim Thwaites, Jack Fletcher are talented midfielders but they aren't men yet imo.
Realistically 6-8 will leave in the summer and maybe 6 come in.