There have always been occasional demands for recount, but there has been a sea change.  Ever since Bush vs. Gore, it has been routine Democratic practice to challenge the legitimacy of every electoral defeat (and after Trump it may become routine for Republicans too).

Expect another sea change.  Future chroniclers will say that with Clinton vs. Trump, it became routine Democratic practice to attempt the impeachment of every victorious opponent (and before long Republicans will probably imitate this move too, if only in self-defense).

There may be a third.  We have already seen the perversion of the machinery of justice to attempt the legal assassination of political opponents.  Let’s see whether that becomes customary too.  And let’s hope it doesn’t ripen into physical assassination.

The danger of such changes can hardly be exaggerated.  Republics can survive a certain amount of fraud.  No republic can survive the widespread conviction of its own illegitimacy.