Ever since the way that S3 premiere wrapped up the previous season's cliffhanger, that's how I've been approaching the show. Half-episodic and half-serialized. Now that we still have **at least** six more seasons to look forward to, there's no doubt we'll get more one-off episodes in the long run.
Take "Never Ricking Morty" to heart and just allow the writers to do what they want so long as the show is still creative and fun. Don't focus too hard on some "endgame." Dan & Justin probably don't even know what that could be yet.