Sancho, Grealish, young player development. Possibly/probably coach that can get them up to the next level (think Ole will peak at top 4 level regardless of players). After team settles with that for a year, summer 2021 look at upgrading weak points (possibly CB to partner Maguire, possibly left back, possibly holding midfielder, along with squad refreshing with older players leaving).
Gk: De Gea, Romero, Henderson long term
No issues
RB: Wan Bissaka, Dalot, Laird as youngster
No issues
CB: Maguire, Bailly, Lindelof, Tuanzebe, Jones, Smalling
Smalling likely off. Maguire is good. Bailly potential but always injured, in last chance territory IMO. Tuanzebe fine as squad player, not sure he has what it takes to be a starter. Lindelof not good enough but fine as squad. Probably buy one if Bailly can't stay fit. Revisit summer 2021.
LB: Shaw, Williams
Fine for now. Summer 2021 or 2022 revisit if we need more going forward from the position and neither of them really convince by that time.
Midfield: Bruno, Pogba, Fred, McTominay, Matic, Pereira, Garner, Gomes and Mejbri as youngsters
Pogba likely gone, hopefully Pereira gone, hopefully Gomes stays and we'll have 3 excellent youngsters to provide depth. McTominay, Matic and Fred is fine as a group of 3 for the base of midfield, but also wouldnt be too big to have an upgrade with a top player there. Revisit summer 2021 for DM (especially with Matic likely leaving then). I'd take Grealish though and add to the quality in midfield. Can find different combinations between the players we have against different opponents, would be fine and give good cover and boost in quality.
Attack: Martial, Rashford, Greenwood, Ighalo (on loan), James, Lingard, Mata, Chong
Chong probably gone, Mata bit part, Lingard squad player, Ighalo short term loan, Greenwood not going to be starter level for a bit yet. Missing the 1 starter at right wing. Sancho the dream. Summer 2021 see if we need to do anything more with CF, between Martial and Greenwood I think we're ok though, provided we get Sancho at RW.
Matter of giving the young squad time to gel, while they progress don't fall behind on replacements when needed. Sancho and Grealish give loads of starting 11 quality and gives us enough depth, just needs time for them all to peak. In that time, change the manager to someone who can reach the top, as that potential team could compete for everything.