Well, the more money he raises now the more attractive he becomes as a running mate for Shrillery. Smart move on his part.
I really don’t know how likely it is that he is Hillary’s VP choice. It’s pretty rare for a candidate to choose one of the also-rans as a running mate, when you look at the history. In this case I think she may be afraid of him upstaging her, and that the non-die-hard dems will look at that pair and think “So who’s actually going to RUN things, ‘cuz neither of THESE TWO can!”