In the long run, less-free societies using free speech as a Trojan horse to disrupt our social cohesion will probably be the end of the US.
It’s not like anyone can feasibly invade or anything, and we’re the world reserve currency so it’s not going to be financial collapse. Meanwhile you see Russia and china very successfully exploiting the infowars/foundations-of-geopolitics tactics etc.
Untrammeled free speech is quite likely to literally be the thing that kills the US.