Have you followed some of the recent discussion around rel="alternate" to get around the issue of proper use of microformats in WordPress core and/or themes? This could really accelerate the uptake for a great many.
Somewhere there’s a note that GWG has already built a big chunk of code into the Webmention/Semantic Linkbacks plugin that implements a large chunk of the work already. There’s also some work done in https://github.com/indieweb/wordpress-mf2-feed as well.
Micropub Plugin work for WordPress
It will include a Media endpoint
Code for integration with the WordPress REST API
This sketch solution may be an end-around the issue of getting WordPress (or potentially other CMSes) Themes to be microformats 2 compatible, and allow a larger range of inter-compatibility for websites and communication.