He should go, but it's not really his fault, just a question of balance, as shown by Lindelof coming on. We need another DM. Fred got bypassed easily on the first Leeds goal, and that's what having a DM is for.
Sabitzer has to stay. He's a quality player with 2-3 years left, so not much resale value, but it seems like Bayern would take 20-25M for him.
So, now we look like this:
-----------------------------------------------#9(Rashford, Weghorst/Martial)
Rashford(Garnacho, Sancho)-------------------------------------------------Antony(Amad/Pellistri)
----------------------------------------------------Bruno(Eriksen, Sancho)-----------------------------
---------------------------Eriksen(Sabitzer)--------------Casemiro(DM)-------------------------------
Sell Fred to Serie A for 15M, McTominay to a Prem team for 25M and you've got Sabitzer's fee covered and 15M of the fee for a DM, which is probably about half of what you need for one we like.
No idea who that would be, but there are DMs who can play a bit around, teams like Palace (Doucoure), Fulham (Pahlhina) and Villa (Kamara) just got theirs in for 30M or less this past summer. We can't offer as much playing time, but at least the same in wages (higher than what Doucoure got surely but Fulham and Villa probably paid decent amounts to get those guys) and it's United and Casemiro is old enough that a player might fancy his long-term future here.