Biden in fourth place.
It is becoming more likely that Trump will face Bernie, who is no Hillary and who has strong support from Independents.
Bernie Sanders leads the Iowa Poll for the first time, just weeks before the Iowa caucuses
As I'm typing a response to this, the phone rings (NH) and it's a message from Team Bernie.

Too funny.
I'm not sure I'd make book on Bernie being the nominee. The election is a long way off and a lot can happen. I'm going to stick with my original prediction that Democrats will choose the "safe" option in Joe Biden (who will continue to stump the line that only he can beat Trump).
That being said, Trump better hope that Biden is the nominee and not Sanders. Because Joe Biden is the only candidate he stands a chance against in not looking like the inept policy fool he is when the time comes to debate. Anybody else (in the top and even middle tier) eats Trump for breakfast. While that wouldn't necessarily cost Trump re-election, it won't be a good look.