There's no "conflict". They don't really care about holidays etc., it's all marketing/number-related and they wouldn't delay a patch because of usual IRL stuff. Blizz is a creature of habits and often goes like clockwork. They'll follow their schedule as closely as possible just like they've done in Legion and so far in DF.
It means 10.2
should be on October 17th > raid on 24th > RWF will pretty much be over by Blizzcon. If it isn't done, they'll either have a few people staying at the office or fix the bugs on Monday, after Blizzcon. It's already happened in the past that a raid was ongoing but employees were on holiday and they handled the bugs after their holiday (Nathria is the most recent one IIRC).
Yes and no doubt it's intentional. 2-years long expansion has been their go-to formula forever. I understand some people would maybe like shorter (or longer) expansions but pragmatism, facts and/or stats are better suited when trying to imagine what a company would do
In addition, and not targeted to you specifically, the amount of people believing there won't be a 10.3 is too damn high. There will be one, guaranteed. Even with a 10.3 (which
should be in April), you still have time for a 10.3.5 and a 10.3.7. That being said, x.x.7 are supposed to be prologue to the next story chapter but since an expansion would be next, it doesn't have to be here. The first big patch (11.0 here) is already the prologue to the actual expansion release anyway, they might as well use 10.3.7 for an extra fun bit if they wanted to.
As others have said, the Shadowlands fated season was unusual and most likely there to limit people quitting the game/show the content to newcomers/returning players while waiting for DF. They said they were happy with it and they could do it again in the future. It's not guaranteed by any means, it's an open door. 4-season (or tier as they were called before) expansion is usually the norm. The cases where it was different are the fucked-up/cut content expansions aka Cata/WoD/SL.