Barnaby is pretty fair - he's been hyping McDavid as on another planet, even above Crosby since he got into the league. So when he starts saying this, I believe him. I believe it myself anyway. The company is a disaster - who would want to stay?
No, I don't blame him either. McDavid is not a selfish guy at all, and he signed a 8 year deal, so I could see him maybe waiting for another 3-4 years, but the problem is the same in either scenario: the Oilers need to be better otherwise McDavid will want out.
I also think there is a difference between being "kinda okay", where you are bouncing around between 6th-10th all season, and really bad (like now), where you are out of the playoffs since December. In the "kinda okay" scenario, I could see McDavid playing out the full contract. That being said, it wouldn't surprise me entirely if he asked for a trade this off-season either. The organization is a complete and utter disaster, and it likely to remain a shitshow as long as Katz is the owner to be honest.