"Killington is in the middle of Vermont, halfway between NH and NY"
Yeah, that's why this is just a joke. I don't think NH would want to take a city in the middle of Vermont even if the Vermonters wanted to give it to them. On the other hand, this is the kind of publicity stunt that folks rally behind to make a point.
It's sort of like the Minnesota thing a few years ago where the MN Senator proposed to give a small piece of MN to Canada. Everyone knew it was going no where, which is why he did it. But it gave him some attention and made the locals feel important.
Vermont used to be part of NY. Maybe they could just give Killington and everything south thereof back to NY.
In 1970 there was a proposal by some people in western Nebraska to separate from Nebraska and join Wyoming...again, caused by dissatisfaction with the state government, and with no realistic chance of it actually happening. Anyway it would have failed if put to a vote in the area in question--the Cornhusters were on the verge of winning three Orange Bowls in a row.