I don't see Sanders being swallowed up by the Clinton campaign. He ran, he said, because he didn't want to see Clinton unopposed. He switched his allegiance from "independent" to "democrat" just so he could. He's always been an oppositional figure, a gadfly in the machine, and just because he (probably) won't win this time doesn't mean he's going to roll over and play dead.
I mean, yeah. He's not going to say nice things about Clinton. Already isn't. But he's going to say less nice things about Cruz/Trump/DarkHorseduJour.