Thank you! This helps for sure, and reduces the panic.
But:
are both still very valid points.
I think what many of us are arguing isn’t that X feature should or should not be supported by Y version for Z time, but that Discourse should offer graceful degradation, maybe something like a plain HTML + HTTP POST mode like the earliest forums offered. Ideally that would be prioritized over new features, especially over cosmetic changes, but I’d argue also over performance optimizations.
Discourse users shouldn’t have to choose between community and new features — and that part of it DOES seem like a cultural question. It seems the devs want to “move a little fast, not too fast, break a few things but not too many”. That might be a perfectly reasonable position for a software company to take, but it is NOT necessarily the same position that Discourse communities would want. Some communities would want to move faster while others would prefer much slower or no movement at all.
To me, Discourse today is already “good enough” and if there were an option for hosted customers to choose a long-term support branch with no new features added for the next 10 years, only critical security fixes, I’d totally choose that — even if the new version were 10x faster. I’d much, MUCH rather have a slow forum that everyone can use than one that gradually loses users just to provide a faster, shinier experience for the survivors.
But not everyone would agree with that. That pace that would be way too slow for both the devs (I presume) and other Discourse communities… it totally depends on their user and device demographics. A forum for old folks won’t ever chase the same features as an AI forum, for example.
But they shouldn’t NEED to fight each other like that. These aren’t mutually exclusive goals. Graceful degradation has been a basic principle since the earliest days of the web, and Discourse is already headless enough (with various APIs, and also proven by third-party implementations like Discorkie) that it should be possible to provide a “simple HTML” mode with basic reading + posting. It doesn’t need fancy themes, it doesn’t need infinite pagination, it doesn’t even necessarily need editing and notifications and all the other nice-to-have features. It just has to be a basic usable experience that lets people still use the forum for its intended function, reading and posting. It can offer nothing more than a 90s Usenet-style UX and it’d still be better than cutting people off completely. With a little more dev time, it could offer a vBulletin style PHP era UI and that’d still be a huge improvement over the “Sorry, you can’t post anymore” situation (that we’ll still see in July).
IMHO Discourse is (or should be) about community above all. It isn’t a tech demo (anymore), and while my personal preference is that it be thought of as “stable, boring software” that rarely if ever changes… I understand that’s not what the developers, and other Discourse communities, may want. That’s fine. It’s not a bank mainframe 
But conversely, it also doesn’t need to chase constant browser improvements (which will never end). In between the two extremes, a basic HTML mode would let users keep posting long after their browsers are obsolete, while also allowing faster feature development on the main branch because users will have something to fall back to.
As a bonus, it might actually let you actually target the kind of time-window based development you want to do (e.g. “we will support browsers up to 2 years old, or at the 95% caniuse mark”) rather than cherry-picking individual features across every possible permutation of hardware + OS + browser + fork. Anything older than that target can still post via the basic HTML mode, but will not be able to use the latest themes, _____, ______, _____ etc. (which is totally fine because they probably don’t care about all that anyway). It frees you having to cross-check every feature against every browser… if a user can’t use some fancy feature, well, it really would be up to them to upgrade to a new browser. But at least they wouldn’t get kicked out from their communities.