And of course Hillary's VP will be the presumptive nominee, so will the Dems even go to the bench?
Depends on who it is. Is Tim Kaine exciting enough that he's going to clear the field? I mean, in this scenario it will have been 16 years since there was a truly contested Democratic nomination fight (I'm not counting 2016 as being "contested", since Clinton alreay has it won), and surely there will be a number of potential candidates who are sick of biding their time and deferring to the frontrunner.
While there's a tradition of VPs ending up presidential nominees, more recently… Assuming Hillary is the nominee, that will mean only 1 of the last 4 VPs was nominated for president. If Biden runs, that will be 1 of last 3 who ran won the nomination. I doubt someone like Kaine would be as strong a frontrunner as Hillary is this cycle.