McDavid will leave when the Oilers realize his trade value vs his 12.5 mill cap hit no longer makes sense. It starts this off season when they have to decide to keep Draisaitl for one more kick at the cat and then lose him for nothing or trade for future assets. The thing I read recently that I can't stop shaking my head at: Nurse makes the same as Makar. If you pay these 3 that much, not enough is left.
The Oilers have been lucky that guys are willing to ride McDavid's coat tails in hopes of getting a cup but when it is obvious no cup is coming they will want to get paid and Oilers won't be able to.