Tolerance for free speech that’s disruptive to social harmony and order is a distinctively western thing. East Asians aren’t big fans either. Which is fine. We don’t all need to be the same.
Edit: it looks like you've been using HN primarily for political and ideological battle. We ban accounts that do that, regardless of what they're battling for, so please stop doing that.
I think your prognosis (which comes across as fear actually) may come to pass, but it will not be because US population is no longer primarily of European stock (some word!)
The primary driver has always been and remains culture. And culture in our age is an industry. And industry is subject to law & market. Liberal values are eroded because of the cultural content that undermine its validity and appeal. Non-Europeans will respond, I assure you, just as readily to formative cultural forces that engender an appreciation for liberal values, as do their "Anglo" fellow citizens. Likewise, both Anglos and the rest of us will also respond accordingly to cultural forces that are otherwise.