Well first, they need the right GM to trade him. If the Oilers do trade McDavid, they'll also maybe trade Draisaitl, Nuge looks bound to retire an Oiler.
But I think by between 2020-2022 he gets traded if the Oilers continue to regress. I think the Oilers might be a consistent playoff team again by the 2030's because that team WILL take a long time to fix up and get straightened out. I mean they need a guy to come in and straighten it all out, as it stands right now the Oilers management is just super dysfunctional.
A Lindros-like trade COULD help the Oilers. But the problem is that I think this team is stuck in a black hole for a long time. This is just a situation of management, not really the players, and considering they've always had bad management, this will take a long time to fix. The sad part is this could've ALL been fixed as early as 1995, when Shayne Corson was captain, aka the worst captain in NHL history.
The teams I see McDavid being traded to are likely Tampa, Toronto (if they have the respectable amount of touchable assets), Winnipeg, Vegas, New York Rangers or Chicago. The proposals will have to wait until McDavid does ask for a trade.
I don't think anybody should blame him if he wants a trade. We just blame Oiler management. The sad part too is there's almost no way Katz gives up the team, and he's not really the best owner. The only thing Katz is good for is the money.