Is there really a need to do that to such a huge degree? I mean, there is barely an experienced, proven, quality CB left. Probably just Martinez and with his injury record the past year, that would be a worry.
Replacing Varane with Branthwaite and Maguire with someone in the mould of Bremer/Todibo would also bring down overall cost. Selling Lindelof and replacing him with someone like Hermoso would be like for like.
In midfield offloading Donny (and not signing Amrabat) should give room for a new midfielder. That would leave us with Casemiro/new, Mainoo/McT and Bruno/Mount + Eriksen.
Upfront we should also be able to stay cost neutruel by replacing Greenwood and Martial with a striker.
If we sell aswell Sancho there should be further room to invest in the attack. Maybe in someone flexible like Eze who could play both in attack and midfield?
Yes, we will likely have to take a hit/make impairment on players like Sancho and Donny. But we will also make profit on players with book value = zero (Maguire, Lindelof, Mejbri, Greenwood, Pellistri).