This is simply not true. The party has moved left in a variety of ways beyond social issues. The party has moved away from the Clinton model. I seem to recall Romney making a big stink about work requirements being removed from some welfare qualifications. The party has moved farther left on taxes. The party has moved left on the environment in terms of advocating carbon based taxes. The party has moved left on healthcare. Obama has reversed much of Clinton's "the days of big government are over" take on the economy.
Sanders has constantly talked about manufacturing returning to the United States. "Renegotiating trade deals" is not a solution. The jobs are gone, period. Unless he wants to support lower worker wages which he doesn't support (and neither do I).
Sanders' plans revolve around magic and have no financial or political means of occurring. "Mass mobilization" is not going to cause Paul Ryan to raise taxes by enough to pay for free college, healthcare, etc. Sanders can't even mobilize voters enough to win the democrat nomination or match what Obama did in 2008.
I'd argue Sanders fans DO believe this stuff is happening tomorrow because they have clearly rejected the tenants of progressive change. A progressive can look at Obamacare and tell that it is a trojan horse for single payer, and given the inevitable demographic shifts of this country it's going to happen eventually. You further expand Medicaid under the law by increasing the income requirement threshold, change the name, increase hospital reimbursement fees, increase taxes, and boom you have single payer. A Sanders supporter looks at Obamacare and wants nothing to do with it while advocating an entirely new system that will cost more and has no chance of passing congress.
I voted for Sanders in my state's primary because I respect him. But he has no idea how any of this works and is clearly less versed on the issues than Hillary. As someone who works in finance I want to bang my head when I hear him talk about banks. He doesn't understand how any of this works and can't even explain how he'll "break the banks." Last I checked he doesn't support nationalizing them either.