In my opinion, there are really two pathways. One in which the government successfully reduces the burden of ethnic rebels to maintainable levels, and one in which they fail and the breakup of the united states becomes inevitable.
Trump's dillema is not unlike Gorby's or more closely, Slobodan milosevic's. Slobo was nominally the head of Yugoslavia, but by stoking ethnic tensions while not having a majority ethnic mandate he precipitated the Balkan wars.
This is usually presented as a lesson in why ethnic grievance politics are evil. The atrocity of those wars speaks to that. But one lesson from it is not examined, which is that the correct leadership choice should have been to create ethnically cohesive structures based on a majoritarian population's wishes BEFORE it had become a league of many like yugoslavia. Of course in that instance each was a highly distinct population to begin with, but in America's case they become like the balkans(fragmented, bickering, and mutually angry) or India before the split only if they continue to allow demographic trends to unfold as they are now.
Thus, the tolerance of multiculturalism is sleepwalking a once cohesive country into crisis which will end in bloodshed. It is impossible to have a happy polity when ethnic division and grievance reaches untenable levels. The only way to get back is to reverse them, to be mean in the short term for a long term gain. Whereas the quo to continue will mean the death of the west beyond the shadow of a doubt. We've already had many examples worldwide.