At this phase in the run, the punditariat is greatly,
greatly more confident than the facts justify. I don't mean that specific to this year... I mean generically at this phase of the campaign. If the punditariat was correct at this phase, Hillary Clinton would not currently be able to run, because she'd be finishing out her second term, having defeated Rudy Guiliani in the 2008 campaign by a small but significant margin.
Note how they would have gotten both candidates wrong.
My rule of thumb is that whoever is leading at this phase of the run is not going to be the candidate. It always seems nailbiting at the time but it's been right for all the years I've been paying serious attention to the campaign, which is about since 2004 or so. (I recall paying attention to both Clinton campaigns but not the primary fight; I was in high school for them. I don't quite recall the 2000 primary fight well enough to remember if Bush was always the primary frontrunner; my memory says no but I've learned not to trust it, and I can't name names as to who was.) Someone older than me may be able to recall a counter example.
So, yes, I'd say Bernie Sanders is definitely in it. But I won't repeat the errors of the general punditariat and make wild proclamations about how much he's in it. It's still not out of the question another Democratic contender that's little more than rumor right now could pop up and dominate with surprising swiftness... IIRC that's a fair description of how Obama got to the Presidency.