I'm curious about this one because the writeup basically says this
will create things that aren't SVG. Is there a plan to make a new
file extension at some point? It would still be mostly SVG, just
augmented with extra stuff. The Inkscape-specific extension would be
like a warning -- "This is not plain vanilla svg and may not render
correctly as such". Kinda like how .ai files are mostly just regular
.ps files, but if it doesn't look right in your .ps viewer, you know
you should try it in Illustrator.