The unfortunate truth is that there are mostly only much more authoritarian countries to fill any leadership void left by the US. As flawed as it is, and as flawed as Trump is, European countries can only step up so much to keep liberal democratic societies as the global ideal.
My worry is that the current regimes of Russia and China are on the political upswing faster than the European experiment and struggling or young democracies in the developing world can stand the test of time.
Enthusiastic participation by America in upholding the idea of liberal democracy (even when it's imperfectly executed) can tip the scales.
The way that happens is by the head of the government reversing course as smoothly as possible from admiring and praising autocratic regimes to giving hope and comfort to democratic allies. Whether it's President Trump, Pence, or fucking Mark Zuckerberg doesn't make too much of a difference in that regard.
