I hope Bernie does run in 2020(if he hasn't died of old age by then). Trump will win because the momentum isn't as great as it was in 2016 for Bernie. It will be the nail in the coffin of all these socialists dreaming of free college, free healthcare, and free whatever else when he loses.
Who cares? They are all loathsome. I actually identify with the Bernie supporters who objected to the corruption and corporatism that has taken over our government. It's just that the stuff Bernie wanted would have been even worse, much worse actually. Voters are clearly frustrated. The republican leadership is disgusting in their lies and cowardice, the democrats are even more vile with their outright treachery.
I care. These people care. The movement has gone ballistic. Let me clue you in. The Neo-Liberal wing that is the current Democratic Party is aging and dying off. The millenials believe in very different politics than the boomers, and they support Sanders style politics in overwhelming numbers. But set that aside for now. Consider that the Bernie Sanders wing of the party numbers somewhere around 25 million+ people. Consider that Bernie Sanders in poll after poll is overwhelmingly the most popular politician in the US. If the Democrats don't move left and we lose the primary, it will be third party again for us in the general, or even Trump, for many of these people. So, either they move left in a meaningful way, or they lose. There is no longer a middle ground. There is no compromise to move to the "middle". This is a game of chicken, and we took the steering wheel of the car and threw it out the window with the pedal to the metal.
Interestingly, this mirrors the battle in the republican party between the establishment and Trump populists. If the Trump populists and Bernie supporters could find common ground, they would be formidable.