This is not surprising. The extreme distaste those born after about 1971 have for Trump was evident in the GOP primaries as well.
As many over 45 will no longer be voting in 2020, I believe this gives Trump reason to worry, even if, as some reports suggest, the next wave of new voters is a bit more "conservative" than the last.
Gen Z is probably gonna be the anti-thesis to millennial. Generation 9/11 grew up on patriotism, support the troops, and war video games like CoD. If anything I expect more of a social libertarian streak but they will not be liberal or more so than millennials on economics and domestic issues. The universe must remain in balance so generation 9/11 must cancel out the SJWs
Practically no portion of GZ is even eligible to vote yet (none are by some measurements). The generation you're describing as "9/11" are Millennials, and with particular note, the events you described occurred concurrently along the politically-formative years of the segment of Millennials who are the most Democratic as a whole (those between 25-30 years old).
The reasons you list for why they'd be Republicans are many of the reasons why they're Democrats in the first place.
Aren't there some polls that suggest younger Millenials are a bit more Republican than older ones? Or maybe it was just younger White Millenials? Ancedotally, that is what I have noticed - the people I know who are 26, 27 and 28 tend to be more Democratic than those who are 23, 24 and 25.
No. Clinton did as well among 18-24 as she did among 25-29.
Clinton may have, but other recent elections did paint a very different story, including 2014 and very limited data about the very youngest voters in 2012.