Maybe they could also drop support for older x86_64 CPU's, releasing more optimised builds. Most Linux distributions are increasing their baseline to x84-64-v2 or higher, most Firefox users (>90%)[0] seem to meet at least x84-64-v2 requirements.

[0]: https://firefoxgraphics.github.io/telemetry/#view=system

[1]: https://firefoxgraphics.github.io/telemetry/#view=general

And doing security updates on ESR for a year is decent. (Though people using non-ESR stream builds of Firefox will much sooner have to downgrade to ESR, or be running with known vulnerabilities.)

If it turns out there's a significant number of people who really want Firefox on 32-bit x86, would it be viable for non-Mozilla volunteers to fork the current ESR or main stream, do bugfixes, backport security fixes, and distribute that unofficial or rebranded build?

What about volunteers trying to keep the main stream development backported? Or is that likely to become prohibitively hard at some point? (And if likely to become too hard, is it better to use that as a baseline going forward with maintenance, or to use the ESR as that baseline?)

  Distro       | Release | Support | Extended Support
  -------------|---------|---------|------------------
  SLES 11      | 2009-03 | 2019-03 | 2022-03 | 2028-03
  RHEL 6       | 2010-11 | 2019-08 | 2024-06 | 2029-05
  Arch         | 2017-11 | *Ongoing releases via unofficial community project
  Ubuntu 18.04 | 2018-04 | 2023-05 | 2028-04 | 2030-04
  Fedora 31    | 2019-10 | 2020-11 | N/A
  Slackware 15 | 2022-02 | Ongoing, this is the most recent release
  Debian 12    | 2023-06 | 2026-06 | 2028-06
  Gentoo       | Ongoing

That's nice... When this was originally posted on 09-05 it just mentioned "32-bit support", so I'd been worried this would be the end of me using FF on a Microsoft Surface RT (armv7, running Linux).

It's fine to keep hosting the older versions for download, and pointing users to it if they need it. But other than that, I see 0 reason to be putting in literally any effort at all to support 32-bit. It's ancient and people moved on like what, well over a decade and a half ago?

If I were in charge I'd have dropped active development for it probably 10 years ago.

It crashed NON-STOP. And it would not remember my profile when I shut down, which made the crashes even worse, since I lost anything I was working on.

I finally figured out the problem, switched to 64 bit and it was like magic: Firefox actually worked again.