I think it is very likely that Sanders supporters were key in tipping the rust belt states. Whether that was done in spite towards Clinton and the party or they bought into Trump's message is questionable though. Probably some of both.
Sanders looks like a lock to win those rust belt states over Trump. However, he risks losing a lot of other light blue states and swing states in other parts of the country.
The poll in this article does a good job of showing this:
http://centerforpolitics.org/crystal...nd-the-nation/
This whole talk that only elites want a centrist ignores all the suburbanites who are fairly moderate, and fairly against socialist policies. This is the group that has been making blue waves in the last few mid term votes.
The video above touts the popularity of medicare for all, but ignores all the polls that show it being very unpopular when it is explained to them that they will lose their employer coverage. This is where I see Sanders falling apart in the general election. The other democrats are going pretty light on tearing down Sanders policies as to not alienate the left wing. But in a general election, there will be all sorts of ads from all sorts of groups reinforcing the fact people will lose their employee coverage and tearing down some of Sanders other overly simplistic policies.