I'd say absolute bare minimum is a striker, a midfielder who can play as a 6 and 8 and then a Maguire replacement at RCB assuming he goes. It's conceivable that 100M could cover the striker, then Maguire and Henderson the CB money and then McTominay and smaller sales (probably one of Elanga or Pellistri since they have value, VDB) the #6/8 though would be tight if we're talking 40M or so.
I can live with one more year of De Gea, Wan-Bissaka and even Martial/Rashford as the backup 9s.
But if the budget is this tight, I could really see Sancho getting sold, that's the highest value player who could end up 3rd on the depth chart pretty easily (Garnacho keeps developing, Martial stays healthy and Amad does well backing up Antony). I think it's possible Ten Hag thinks Martial is a better striker than Sancho LW, but we can't sell Martial, while we can probably still get 40M for Sancho from an ambitious mid-table prem side with cash to burn.