Since TLS 1.3 will require a fallback ( issue #630165 ), we will have to take on the task of finding version-intolerant servers, reaching out to administrators, finding the affected vendors, asking them to fix it, and then going back to administrators and asking them to take updates.

This will mostly be non-code changes and lots of the behind-the-scenes contacting people we did for the previous fallback, but filings this so I remember to do it. Also to add metrics in Chromium where we need it.

In addition, we should, with very very careful safeguards (at minimum, gated on a field trial), lie in our ClientHello and advertise random high versions during periods when the TLSWG promises not to work on TLS 1.4.

Unlike the version-list extension proposal, it will require a ton of continuous manual care to keep from messing up, but we'll try it.