10? This was a problem even before 2001, which is when Internet Explorer 6 was released which (unfortunately) quickly became the Internet. Things weren't so multi-platform back then so swaths of the Internet became inaccessible unless you were using IE6 on Windows. Things are a bit different these days with smartphones and Apple's viability, but the landscape is starting to look strangely familiar.

Many have warned, most have not understood or unfortunately cared enough to listen. Now we are fighting the uphill battle for it.

One thing could be to define layered standards for various use cases.

Like the archiving standard for PDF. Perhaps a formalized version of “graceful degradation” if you will with a known set of target.

One target could be a self contained, script-less, bundle f.ex.

Test everything in w3m, netsurf and other niche browsers.