Quite possible, we are looking at an election result not seen in a long time...
True. The 1984 landslide victory of Ronald Reagan over Walter Mondale was 32 years ago.
Mondale was a horrible campaigner, someone nominated for his long service to his Party and being overall a decent fellow in an impossible year, running against an effective incumbent.
Donald Trump is singularly inexperienced in electoral politics; he is an awful person; he has been a poor campaign strategist; and to top it all off he has won the nomination of the challenging party in an open-seat year. Sure, the incumbent President has been one of the better Presidents in history... but that means little this time.
With someone reasonably competent running for the Presidency, like Kasich or Romney, the Republicans should be winning the Presidency decisively.
Here are two of the worst blow-outs in open-seat elections:
1920 1952In both cases the Party recently out of the White House followed a troubled President. But something is very different this time. The incumbent President isn't troubled.
Here is the most recent case of the 'outsider' Party nominating someone to follow a troubled President:
2008 Even with so many things going wrong for the Republican Party at the time, Barack Obama won by Reagan-like margins... but in only about half the states. He lost by Mondale-like margins in about a third of the states. That's how cultural polarization works.