The most terrifying thing about this election cycle is that there is a chance Donald Trump could end up in the White House. I continue to think that outcome is unlikely, as the nation's changing demographics constrain a strategy of appealing to angry, resentful white people in the general election in a way they have not in the Republican primary.
Still, Republicans have spent the last several decades making it increasingly difficult for non-white people to vote, so there is a chance Trump could win.
The second most terrifying thing about this election cycle is that, even if Donald Trump loses, I am sure there are any number of equally appalling, quasi-fascist/eliminationist goons watching this campaign and learning from Trump's mistakes and failings. You can be sure that they will be ready at the next opportunity, and if this cycle has proven anything, it is that the Republican Party is essentially a failed state, ready to be taken over and exploited by any demagogue who shouts loudly enough and can figure out which levers to pull.
In other words, it is is going to be a lot easier whoever creeps out from under the rock the next time around than it has been for Trump in this election.