Yeah, the cleanest move, assuming we're staying with a 4 man defence, would be something like this next summer:
Out - Shaw, Maguire
In - top young RCB before he costs 70M, like Leicester or Arsenal getting Fofana or Saliba, 1st choice RB, doesn't have to be super young, literally the best player available since Dalot is a backup at this level. Presumably Ten Hag wants Timber. Malo Gusto, Livramento (if he comes back good from the injury) and Vanderson look like stars of the future and will move to bigger clubs for massive fees presumably. Might not want a little guy like Frimpong or Lamptey since we already have Malacia and Lisandro on set pieces in defensive positions and if Sancho and Antony are our wingers they're not marking anyone either. Basically we'd just have Casemiro, the RCB, our #9 and that's it in terms of guys who could mark.
Malacia(Fernandez)-Lisandro(Lindelof)-Varane(RCB)-RB(Dalot)