The republic was already in peril.
By this time next year, if all goes as Trump and his cronies and coattail-riders have explicitly and repeatedly clearly stated they fully intend, the republic won't be in peril - it'll be dead, and a plutocratic/christofascist oligarchy under the rule of an all-powerful dictator will have been built on its corpse.
That threat didn't suddenly spring into being yesterday - it's been there all along.