You really don't need a rebuild, you have a much better squad than most give credit for on the caf.
It's no secret that you need a left sided wing back, but apart from that you really don't need to do much business.
Evans, Lindelof and Eriksen will leave at the end of the season. Maguire has another year option on his contract, if the club are feeling tight they can just extend that and with Yoro and De Ligt bought in the summer you don't need another CB.
If you keep Shaw you have Martinez, Yoro, De Ligt, Maguire and Maz who can play across that back three, I don't know if you have any good CBs coming through the ranks, but I imagine they'll be looked at first, though the interest in Branthwaite looks quite serious.
If Casemiro goes as well as Eriksen , then you may need a new midfielder, I don't know if Collyer is good enough to step up.
As for your front line, they won't sell Zirkzee, the premiership is full of players that have struggled to adapt in their first season, I'd be surpised if you sold Rashford, but from an FFP point of view any sale would be pure profit so it's definitely possible. But even if he went, you still have plenty of talented players across that front line.
So I can see you losing 3 or possibly 4 players and bring in a LWB and Branthwaite.