@David's post@David's post mentions Standard Markdown Common Markdown CommonMark, which is an incredibly welcome development - apparently my "It's not happening" was wrong: it was happening on the quiet!
All I want to add is that I think this is the correct way to go about it: the horse before the cart. If we can get a widely accepted standard implementation of markdown on SE first, then we can talk about implementing extensions to the standard later. On the subject of extensions, you may be interested to know:
- Fenced code blocks are in the spec
- There is some discussion about whether tables should be too