Okay sir, this is going to be long winded but hear me out. You seem like you think things through before coming to a conclusion.
So when we are talking about McDavid being traded the first thing is why. Why is he being traded from Edmonton?
Is Edmonton unhappy with him, no. Why would they want to trade him? The short answer is they won't ever want to do that. He's the best player in the world. Would teams ever off up a package that Edmonton couldn't turn down? Sure but that cost would then be prohibitive. Like the current trade proposed here. Marner and Matthews for McDavid is two elite players for the best of the elite players. Two elites still do more damage than one. Otherwise Edmonton would have more than 1 playoff appearance since drafting McDavid.
So its not going to be Edmonton deciding to trade him.
Why else would they trade him? The only reasonable reason I could see Edmonton trading McDavid is if he demands a trade in 2 years when his NMC kicks and and after the Oilers miss the playoffs for the 4th straight season while trying to contend now. Sure this is a long term hypothetical but if that was the scenario, the return is going to be vastly reduced. If Edmonton has to trade him and calls up the Leafs, why would Dubas even begin to contemplate paying a kings ransom for a player that is dictating where he is going and has chosen his team? Even if there are a few teams in the running to get them, who has an elite Franchise centre at a comparable age? Tampa would be another team and the ask would be Point and Sergachev or some other hot shot rookie but not much more, why would a contending team sap too much power from their own lineup to add 1 player.
The best return Edmonton can hope for is a elite franchise young centre and something else but that something else won't be an elite roster player, it'll be a prospect or a pick, or a depth player with upside. Giving up more in that scenario is just desperation and poor management.