Agree with what others have said, we shouldn't be looking to move anyone on unless they want to go.
I can see us losing at least one of Sterling, Gabby or Mahrez, although I'd rather not - but if it's just one of them we lose then we shouldn't need to further replace them considering the other additions we've already made to our front line and the potential we've got coming through the EDS.
Key requirements are a CDM and a full-back.
CDM is relatively straightforward - we need someone to rotate with, cover for and challenge Rodri.
Full-back is a little more complicated.
In our current squad, my right-back preference is Walker, then Cancelo, then Stones if it's an emergency. And my left-back preference is Cancelo, Zinchenko, Ake, then Laporte if it's an emergency.
I feel like the team is weakened more by Walker being injured/suspended than it would be by the same thing happening to Cancelo. Because a Walker absence means either you go to second choice at both right and left-back, or you keep your first choice left-back and play Stones out of position, weakening you at right-back and potentially weakening you centrally too.
So I'd actually prioritise a backup right-back over a backup left-back, although I think our squad is small enough that if the price was right, we could take one of each.
The Cucurella rumours suggest I'm wrong though and the priority is a left-back.