Well, you don't need to be a so-called "doomsayer" to notice that game launched 1 year ago, and we haven't heard a single bit about 9.2 yet, and also likely won't get PTR before Christmas. Remember that it a normal expansion cadence, we would have 10.0 by late 2022. If they manage to push 9.2 before spring, 9.3 will likely launch at the time, when new expansion should happen. So either they skip 9.3 or they delay expansion by quite a bit.
So yeah, it's just people making educated guess rather than being "doomsayers".
And also, just because Blizzard plans to go with "much more" content after 9.2, it doesn't necessarily mean that 9.3 is coming to be honest. And I can hardly see it fit any schedule. Also, they prepare their content long before we even think about it, so it could be scrapped simply to redirect these resources for 10.0 as well