I think if clinton gets the nom, she'd heavily consider making sanders the VP. She is struggling in the enthusiasm factor, the young vote, and even young women, all of who are in bernies corner. She is very much establishment now, so having bernie on her ticket would maybe inject some of that youthfulness enthusiasm in her campaign and help ensure that there aren't a lot of disappointed idealists on election day that just say fuck it and stay home.
In contrast, if bernie wins the nom, I have no idea who'd he go with, but it woudn't be hilary. Not that hilary would accept it. Bernie will be attacked by repubs as a pinko commie, so I would expect bernie not to go too radical with his choice but to balance his ticket with a folksy southern democrat... probably white... or maybe a latino woman. Are there any folksy southern democrats in the party that have pull these days?
If trump gets it.... I see him going with rubio. I think he's burned a bridge with cruz. Maybe he'll choose someone like kasich to bring some normalcy to his campaign.
Cruz... prob rubio again but at this point I am just pulling stuff out of my ass.
Rubio... no idea.