And hot take but Vermont will trend hard right by double digits by 2032 if not 2028.. And yes, I know it's not part of the original 13 but I didn't want to exclude it without every other state on the east coast.
No idea where this idea of Vermont being a "borrowed-time state" comes from. It's as safe D as a state can be. Unlike Trump's WWC coalition, Vermont is not "ancestrally Democratic." Not only did it just flip D at the federal level recently (1992), it's truly progressive. For example, it has the highest support for abortion of any state (70% according to Pew). Don't expect a flip anytime soon.
Maine was safely democratic in 2008 and arguably 2012, and it has near-identical demographics. Vermont is also a very rural, fairly poor state with a small population-it lacks the wealthier suburban areas in the south of New Hampshire. There is much less resistance to trends in a state like Vermont than a bigger, more dense and more diverse state like Massachusetts or Connecticut. It also has a GOP governor.
I'm not saying it will flip in 2028, but I can see it going from D+35 to D+10-15 in around a decade.
I may be wrong and someone can correct me if I am, but I'm pretty sure young people in Vermont are even more Democratic than older people. It just has a unique political culture that demographics can't really explain.