It looks like they are already at the "Extinguish" phase for email. Try reading this:
https://lkml.org/lkml/2020/5/19/1527
:(
https://lkml.org/lkml/2020/5/19/1527
:(
Disclosure: I work at Microsoft (on the Windows accessibility team). At work, I use Outlook. Outside of work, I use Mozilla Thunderbird, but even there I send HTML emails sometimes.
By stating "HTML email has features that most people actually want. The world has moved on...", you seem to be implying that the primary method of communication of Linux kernel developers is irrelevant and their use-case for email is not important. In fact, the more I think about this, this is a classic example of Embrace, Extend, Extinguish.