It's probably a moot point though. Trump has done nothing but build on his support in the Rust Belt since getting elected. Without PA, MI, WI and OH, the Democrats have no realistic chance of making Trump a one term president.
“The Democrats have a serious problem with their bench. They don’t appear to have any superstars rising through the ranks that could run for the presidency in 2020.”
That’s how things looked just before Carter, Clinton, and Obunghole.