The more I think about it...
Biden represents the last acceptable Democrat on all fronts, and that's mostly because of Obama. Which is weird to think about. I think you're first paragraph infers a greater point: there's no one sitting on the bench that can satisfy the party apparatus while garnering any mainstream appeal.
Conversely, Trump is the only widespread acceptable Republican and frankly, that's because he's not a Republican.
Post 2024 is going to be wild.
Hexbear
It's paradise for lost Redditors.