I have a feeling a Civil War will be brewing in the Democratic Party between the Establishment symbolized by Barack Obama,Joe Biden and Hillary and the Young Insurgents in the Party symbolized by Bernie Sanders and his young supporters. I think Bernie and his backers will win because they will have more energy and determination than the Establishment. A bloody Civil War will set the Democratic Party back and it could be a long walk in the wilderness.
If Sanders run he will sweep NH. And he has a very good chance in both NV & IW. If he goes to SC with a 3-0 record, it will be tough to beat him. Even if Obama & Hillary endorses Biden, it will be difficult for him to do the same numbers with blacks that Clinton did (which was shaped by personal Clinton affection, low name recognition of Sanders & huge elect-ability argument vs Sanders).
I could see the Sanders win taking over in a bloodless coup!
I don't think Bernie will run again in 2020. He will be 79 (83 in 2024) and a campaign is really hard work. I do however think he would be a great VP candidate if he is doing well health-wise.
He's only 5 years older than Trump, and in better shape.
https://www.youtube.com/watch?v=ZP_J6gmJYiU