This just isn't how it works. When you get beat on your right, you move right. You only move left when are beaten by or trying to stave off a challenge from your left. Other than specious claims of a glorious revolution, what exactly would a Bernie-like agenda have accomplished? Does the Rust belt want higher taxes paying for free college and universal healthcare, or does it want lower corporate taxes, protectionist trade policies, and fewer non-white job-seekers? Did people in MI, WI, and PA fail to vote for Hillary because she wasn't sufficiently pro safety net?
This seems like a key issue and one that should receive some attention from a ballgame standpoint. Why didn't they try to correct the problem in Michigan instead of taking it for granted? My guess is that polls were off and their polls made MI seem safe. I saw a piece on some show (I think it was the news, but it could have been the Daily Show) earlier in the year, where a union organizer was speaking to his members about the importance of voting for Hillary and what democrats would do for them. The place was nearly empty and had a bunch of people with arms crossed clearly not interested in the message. That seemed worrisome at the time but faded into background as so much else happened.
I do think this was part of the problem. In other words, Hillary's policies were much better for the white working class in the Rust belt, she had concrete items that would actually improve their lives. But she didn't pitch those things as her core message, she didn't try to connect with those people in her ads, speeches, and debate performances. She only spouted policy points in response to direct questions about how to help them. Trump showed that he realized how bad things were for them, shared their anger at being left behind by technological progress, and provided them a set of scapegoats to blame for their problems (i.e., Obamacare, immigrants, NAFTA). I was truly scared when he started beating the NAFTA horse in the first debate, but I got caught up in all the scandalous stuff just like everyone else did. Most people vote their gut. My gut reviles the man for his attitude, his affiliations, and his rhetoric. If those things don't bother you too much then you can be swayed by him saying a bunch of stuff you agree with, even if you know that it will be difficult to implement or perhaps even actively bad. That's why people voted for Bernie too (though there at least they didn't have to overcome vile character traits). For someone whose policy was firmly grounded in her ability to listen to people's concerns, Hillary did a poor job of parroting those concerns to convince people she understood the problem. I don't say that to knock Hillary, who was trying to use her resources the best she could and probably just underestimated the problems with former union-blue states.
Yes, Hillary proposed several things that would help them. The problem is that they don't want to hear about a way forward, they want to hear how to get the old ways back (and, as I said above, Hillary was really bad at the affinity fraud game). Specifically, the ideas of (1) raising the minimum wage so people with jobs in the service sector can live more comfortably and buy more stuff, increasing the need for people to who make and sell stuff, (2) fixing the ACA so that people don't have to remain locked in a job for healthcare and don't have to choose between health and money, (3) making college free for people who make less than $125k would help all these families and their children improve their lives, and (4) investing in the green economy to create new jobs at solar and wind farms and new jobs making the components and designs that go into green products. These things will all help the Rust belt and will all be good specifically for people who are currently hurting by clinging to old, dying industries that keep cutting or outsourcing jobs.
To be fair here, though, Trump has also proposed things that will help these folks. Massive infrastructure improvements would create lots of jobs in a way that would have a lasting benefit for the country. We should have done it in 2009, but even now it would be good. Protectionist trade policy will only be useful if it targets China and even there it will hurt people by drastically increasing the cost of products. People who get a job out of it will be better off that they were without a job, but if a group of friends & family knows 2-3 people without jobs and therefore are all voting for protectionism, then they are hurting the rest of the group to help those 2-3 people. They would be better off with more government jobs paid for by their taxes, but protectionism will still help a little for the worst-off. Corporate tax incentives for bringing jobs to America would be a good way to lower corporate taxes and also create jobs. It wouldn't be better in the long run, because the money is likely to be poorly spent mostly paying the richest folks even more, but in the short term it could create jobs in places that need them most. It only works at all, though, if the tax reduction specifically requires making stuff in the US and not just moving your headquarters here.