Not everyone lives in the northern hemisphere, or call autumn "fall", or, AFAICT, use the seasons over specific months as much as the US.

and Harris and Walz are on the cusp- 1946-64 is the range in the US)

Well, I think that's missing the forest for the trees. If people at the older edge of cusp have been dominant, then shifting to the younger edge, ~15-20 years younger, is still a step change.

Obama kinda marked the beginning of it, but is best viewed as an aberration. His opponents were silent gen (McCain) and old-boomer (Romney, 1947). And the next two elections after him were, in birth years, '46 v '47, '42 v '46. IE, over 6 candidates in 4 elections, Obama was the only one not born before 1948. Both Harris and Walz being born in '64 feels like a step change (where apart from Palin, I don't think VPs were ever typically much younger)

I think they were putting them in gen x and Vance in millennial.

I think you missed the point. Not that they are millennial but that it's the first time millennial are seeing someone born from a different time period.

I think it's nothing. They are a frustrated disoriented group. They'd take anyone.

Maybe so are Dem voters who are excited about Harris, while a few years ago she was rather unpopular.

I've never set foot in the new world, but maybe people should be excited about perspectives of a new major party coming to existence, since GOP is broken. While Harris is just better than Trump, no less and no more.