Perhaps people can go to Outlook.com? What happens if they go to DMARC
p=reject? Everyone can go an sign up for yet another domain?
That just kicks the can down the road, but eventually that can will
take no more kicks.
And then developers can move to fastmail.fm; there are quite a few mail
providers, after all.
And I would expect market forces, combined with mail providers who aren't
trying to send
official bills to consumers that can be easily phished from the same domain
as their customers,
such that there will probably be at least one mail provider that will meet
the need of developers
and other people who need traditional mailing lists as they have been
implemented for decades.
The average Internet user doesn't understand DMARC. The average person on an
Internet mailing list doesn't understand DMARC either, and even the average
tech person on a mailing list doesn't understand DMARC. All they know is that
their mailing list doesn't work, or that they have been unsubscribed. Only
people who work on DMARC understand DMARC.
Asking the average person to switch their email address just so that they can
participate in mailing lists isn't a solution.
--Terry