The Left Is Self-Cannibalizing and Ultimately Little But Bare Bones Will Remain

That's because, as Bruce Thornton observes, it cannot put the brakes on the process of eating itself alive, the better, it thinks, to become even more "perfect" and "virtuous":

The left is caught in a process of perpetual purges cloaked in demands for justice that shouldn’t have surprised anyone who was at all familiar with the French Revolution or the Bolshevik breakdown. The radicals can’t stop. That is what makes them radicals. And their creed of self-righteous extremism rejects any legal or rational norms leaving them with no resolution except outraged political annihilation.

This is the way their world ends, not with a bang but an outraged "tweet".