> Cancelling XSLT is going in the wrong direction (IMHO).
XSLT isn't going anywhere: hardwiring into the browser an implementation that's known to be insecure and is basically unmaintained is what's going away. The people doing the wailing/rending/gnashing about the removal of libxslt needed to step up to fix and maintain it.
It seems like something an extension ought to be capable of, and if not, fix the extension API so it can. In firefox I think it would be a full-blown plugin, which is a lower-level thing than an extension, but I don't know whether Chromium even has a concept of such a thing.