After Microsoft has already (thankfully) dropped support, also other developers are following. The next one is Firefox, which is pretty popular in Germany, if not the most non MS browser used in our country. However Mozilla chooses to support Firefox users with the ESR (Extended Service Release) version of Firefox, but I doubt many average users will be aware about that change nor have the knowledge that they have manually to switch the browsers by uninstalling the old and and replacing it with the ESR release.
Windows XP and Vista are no longer supported. XP and Vista users running Firefox 52 will continue to receive security updates on Firefox ESR 52.