I mean, you can already do all of this (and more) in Pandoc's Markdown dialect, which is CommonMark-compatible. The main things you're getting here are sanding down some of the sharp corners that CommonMark has, in exchange for some uglier syntax if you actually care about the use cases those sharp corners enable.

The point on standardization is sort of moot until Djot becomes big enough to be more than a single implementation. I'd be happy to see it get to that level, but I won't be waiting for it either since Pandoc Markdown is perfectly servicable as it is.