Hahaha, I love how you put that:

Is it the fate of all social media to become a victim of its own success?

We live in a novelty driven world, so I guess that to be the end result of any kind of successful thing out there.
Everything has it's time of Birth, it's time of Growth, it's time for peak Success and then it will eventually become too mainstream to be cool. And then it's time for the Death process, independently of how slow that process is.

Anyway, really nice post! Thanks.