The country is unlikely to break up - the federal government is too massively strong to allow that.
Only countries with weak central governments really disintegrate or have civil wars.
More likely the next 30 years are full of constitutional crises as right wingers declare a new policy of ignoring laws out of DC that they don't like.
And there will be disputed presidential elections, more political violence.
And there will be internal migrations reflecting politics. The result will be ever-poorer right wing areas and ever-richer centrist/lefty places.
When trump keels over dead in 10 years a lot of the gas goes out of the right wing violence tank.