If he could get away with it, he would do it in a heartbeat. He has demonstrated that he has deep hatred for America and Americans, and in his value system anyone who stands in his way must be eliminated.
It's a stretch, but I think it would be wise to think and plan out such an eventuality. It's the logical end to the path we are on now.
Liberals don’t quite have that power, but a more gradual approach is likely, simply by criminalizing conservative freedoms. Make all conservative speech “hate speech”, shut down talk radio, outlaw homeschooling, etc. The need for gulags will depend on the level of resistance.