there are 89 flavors of markdown.

there will never be a standard markdown.

and not just because of xkcd927...

if you have a muddy puddle, you can't make it clear by adding more dirt. you have to replace all the muddy water with clear water.

markdown needs to be abandoned, and replaced with a superior version of light-markup.

(unfortunately, neither restructured-text nor asciidoc is superior.)

sooner or later -- probably later -- the tech sphere will see the need to do that replacement. until then, it would be a major disservice to assert markdown upon the world-at-large.