As the CA/Browser forum said in their response to this, they feel automation is the key. Protocols like ACME do exist, but really only exist for web servers.
People forget that it's more than websites that exist on the internet that use PKI infrastructure. Your printer sitting on your desk -- that's got embedded certs. Have a phone? Yup, that has certs loaded into it as well to do encrypted phone calls. LDAP servers, directory servers, mail servers, API servers, game servers, etc. Hell, that IoT lightbulb has a cert it in, I bet (or you hope it does, if it exposes https). I know I do TLS encrypted between my phone system and my carrier -- it works well but when certs change, stuff breaks because that stuff is hyper-sensitive to MiTM attacks where you need to trust an individual cert for a period of time.
This is going to leave all those devices that aren't traditional apache/nginx/IIS web servers to have a few options:
- Issue private, unsigned certs that have longer validity. Expect users to directly trust those certs (or instruct them to click through errors). This is a huge step backwards and teaches our users to ignore earning when things are wrong.
- Issue certs from a private CA that allows you to control the validity. You then have to teach your users to import the root cert onto every device they plan to use (this is /really/ hard on mobile devices). This works until you need to hit those resources with a web browser, and Safari/Google start to block certs that have validity that is longer than 45 days (and we've seen this in the past when certs went from 3 years down to 1 year).
- Hope that /every/ manufacture puts in cert and key rotation into all their products in the next two years. Even then, how do you validate all those certs for these smaller devices that aren't or shouldn't be publicly accessible on the internet.