Re: Feel the Bern!
Let's postulate an alternate world where Gore won in 2000. The 9/11 attacks would almost certainly still have happened, but with democrats in office for nine straight years at that point the party would have been crucified in the 2002 and 2004 elections as weak on national security. So maybe the Iraq war doesn't happen in 2003, but it might still happen just a few years later. And who knows what wars Gore might have started, hoping to look stronger and in charge for re-election. Even if you're a democrat, it isn't an open and shut case that things would be better if Bush had not won the election in 2000.
Just look at this year's campaign as an example. I think the party that wins the election this fall is a long term loser. If Trump wins, he will make a mess of things and be out on his ass after one term. The democrats will win the presidency in a landslide and likely take both the house & senate in the election four years from now if Trump wins this fall unless he's a lot better president than he is a businessman.
Likewise, if Hillary wins this fall, by 2020 it will have been 12 years of a democrat in the white house, and the republican house will have been opening investigations into everything she does to insure her popularity stays as low as today. All but registered democrats will be thinking it is time for a change, so as long as the republicans don't nominate a nutjob like Cruz they'll win in a landslide and hold both houses of congress in 2020.