Well considering the DNC wouldn't support him and leadership like Chuck Schumer won't even say they voted for him, I suspect there's very little chance of that. If you take a look at the funding disclosures of most of the dem leadership, I don't think there's much reason to be concerned they're going all progressive on us.
I mean look at Maine - a state that could be critical with a senator who should be ripe for unseating. Even before Platner's issues, the party wasn't going to touch him, opting instead to throw their support behind a 77 year old woman who's been a good, but not hugely popular, governor.
But I'm a great believe in state primaries. Let the people choose.