Agreed. If I were to guess a number, I'd say he's probably got 2 years left in him. Dude's basically gambling on getting blessed by the algorithm again.
Dev is at the point where there is nothing he can do. Even if he were to apologize and admit complete and total defeat (never happening) his audience is effectively gone. At this point, he needs an outside party to jump in to bail him out. Even then, this can backfire and kill his channel quicker.
If the man wants to salvage whatever remains of his reputation, he just needs to disconnect. Get off the internet, get a mundane job, and let things cool off for a few months or a year. I'm being sincere. The internet may never forget, but it is retarded. And a year is enough time for it's focus to turn elsewhere. Get off, detoxx, and rebrand. Start fresh. I mean this genuinely.
A pity my advice will be ignored.