XP seems to be a lot of "fun", these days with security especially since the security features XP DOES support are being phased out day by day. for all those who want to drop XP there is always the problem that the people wont be able to access the site, especially since Google Prefers HTTPS now they probably link to HTTPS sites which can easily be not working if they value security more than XP.
they have seemingly no chance of giving the user an Upgrade warning or similar, and here's a question that tries to address this:
is it possible to reverse-proxy users with "bad" security based on their clienthello, so they could be internally redirected to a behind-server with its own certificate (e.g. a SAH1 cert so that even old androids and XP can see it) which could have an upgrade warning, so that people at least know what's going on and provoding them with help to use the site securely and as intended (e.g. with Firefox) and explaining why that's needed without compromising the security of the Main System.