An important thing people overlook is the fact that getting wages off the books is more important for a club like United rather than the sale and transfer fee of current players.
For example, Ashley Young's wages were freed (and his number) before the Bruno transfer.
The natural turnover of the squad results in new wage space that is taken by new players or new contracts, but in this case new players.
Juan Mata - 160K GBP per week, expires June 2021 but a club option thru June 2022
Marcos Rojo - 80K GBP per week, expires June 2021
Phil Jones - 75K GBP per week, expires June 2023 but a club option thru June 2024
(wtf!)
Jesse Lingard - 75K GBP per week, expires June 2021 but a club option thru June 2022
Alexis Sanchez - 350K GBP per week, expires June 2022
Chris Smalling - 70K GBP per week, expires June 2022 but a club option thru June 2023
Odion Ighalo - 130K GBP per week, expires August 2020
https://www.spotrac.com/epl/manchester-united-f.c/payroll//
Currently, three players are on loan (Rojo, Sanchez, and Smalling) with Ighalo's return unlikely due to loan terms.
If three players are going out at minimum, in addition to considering what has been spoken about, it's looking like four potential players - RW/RF, central midfielder, CB, and CF.
I'd be hesitant to put the entire frontline cover on Greenwood supported by James and it's nice having a different CF like Ighalo.
The other three positions, RW/RF, CM, and CB are clear with the RW/RF position the only one where a clear, bang on starting XI international player can walk right into the team (Sancho). Every player linked at CM and CB are not so clear cut starting XI, but they are close to it and should easily push the current starter and be clearly ahead of the immediate back up player (midfield - McTominay and Fred or CB - Bailly).