Sanders could beat Trump in the general. But then again just about anybody beats Trump in the general, and Clinton has had a long time to work on her ground game for the primary. I don't see her losing the primary unless someone really, truly radical appears.

The problem is that Sanders has a message that resonates with a lot of disaffected white male progressives. If you dig deeper, you can see he's not really great on issues of race or gender. Sanders has some momentum, but I think Clinton has a marginally better message on race and gender.

From where I sit, there's still room for a real progressive to show up - someone who can talk about the economic reforms Sanders is pushing, and also sit down for real with the #blacklivesmatter activists about police reform. Someone who could pull both off could beat both Clinton and Sanders to the democratic nomination, maybe. Still time yet, but I'm not holding my breath.

All that said, Clinton possesses a ton of resources for fighting for the primaries in all the important states, and it's hard to ignore that unless her favorables slip underwater, even if a really exciting candidate does throw their hat into the ring.