We already have a standard for stupid anti-UX features built in. It's called NPAPI.
And I seriously doubt with EME that it will change this way. I work for a media company, Flash is used not just for its DRM but because our ad vendors don't care about HTML5 support. It's why we can't move forward with HTML5 outside of mobile.
You do realise that 'mobile' now accounts for > 50% of pageviews?
Which means that your ad vendors actually about HTML5 support. They just do not know it yet.