Any reasonable McDavid trade is going to gut the other teams depth, which is the very problem that would lead to McDavid being on the block in the first place.
Take the hypothetical acceptable offer from Detroit: Larkin/Seider/Cossa. Detroit’s current biggest need is another top 6 center. In trading for McDavid, they lose their current 1C, so they don’t make any headway in addressing their biggest need, but they also lose their current young 1D, and their potential future starting G, creating new problems. In short, upgrading from Larkin to McDavid actually sets back the team at large, creating a similar lack of depth in key positions to what Edmonton is dealing with now.