According to this report, 22% of the US population does not speak English at home:
Both my parents came from homes in Ohio in which English was not spoken.
Ultimately, they did "assimilate".
I think the issue now is what (if anything) binds us together as a nation. And apparently our only common denominator is Trump. Some hate him, some love him, and everyone seems affected by him.
That's not enough to keep us together.