I can see that happening but we'd need Yoro for that to work well. If Martínez is playing left-back, it's likely that we switch to a back 3 in possession where De Ligt is deployed as the CCB, because of his leadership, organizer and communication skills, and due to the fact that he's too slow to be a wide defender and can easily get done 1v1 in the channels against any pacey attacker in a high line, so that should be a no go. Yoro is the only defender we have IMO that's perfect for this.
So it would be Martínez-De Ligt-Yoro in a back 3 in possession, with Dalot/Mazraoui inverting into the midfield next to Casemiro/whoever plays DM.
This would be a great trio to have in possession and for the high line, and also with Dalot/Mazraoui a great quartet for deep, box defending. The only two issues I see with it is Martínez as a wide defender wouldn't be as fast and athletic as you would ideally like, and would also be probably better at CCB so that he has more and better angles for his line breaking passes...but then De Ligt has to be deployed as a wide defender which won't end well.
It will be very interesting to see how our defense is set up both in and out of possession, and whether we add Branthwaite to the team next year, because he would be great as an LCB/LB/wide defender in a back 3 type, but then we'll have 4 quality CBs and it will be difficult to keep them all happy, although usually we have at least a few injuries so maybe actually more depth is actually needed.