> massive corporate penetration

By this standard, every desktop should still ship with a copy of Internet Explorer 6. Most of what made it "special" compared to say, the contemporary Firefox 2.0, was its huge pile of special sauce used only in corporate settings. That stuff had massive corporate penetration as well, but we moved on because ActiveX in the browser wasn't worth the security cost of keeping it around.

If there are important legacy things sitting around corporate environments that literally require XSLT to function, they've had over a year of warning in which to sort it out -- port it to something else, or, pick some alternative browser, pin its version, and set it up with a proxy that can only access your weird XSLT sites. They'll be improving their own security posture with that move, as well!

Random corporations' failure to plan doesn't constitute a need for the rest of the world to continue to maintain obsolete technologies for free.