Not really, and here is why.
Look at how many people, even a few in this thread, dismiss Sanders. They seem to buy into the numbers put out by Hillary’s corporate sponsors that she is THE Democratic candidate. With @kritiper saying “she”, @CWOTUS with “Are you kidding me?”, and @Cosmos going with the people who said Clinton would defeat Obama in the primaries back in ‘07, it’s obvious that a lot of people consider Sanders non-viable.
With corporate news trying to get Democrats to pick an establishment candidate despite polls showing that people on both sides want an outsider (or at least a shake up of the status quo), and doing so with some success, and the possibility of Independent bids from Sanders and/or Trump, I’d say it’s NOT a sure thing.
I doubt Sanders actually will go indie though. While both he and Trump said they wouldn’t, Bernie actually sticks to his promises. That said, either might be a popular enough write-in that no being on the ballot could be moot.
@Cosmos Western Illinois University has predicted the last nine presidential elections accurately. Here is what they say. And lets not forget to keep an eye on Dixville Notch.