It's a minor issue comparing to the issue of DRM. You say - let's worry about plugins, while users will agree to use DRM anyway. I say - if user agrees to use DRM, user can as well use native plugins - such user doesn't care about security or privacy already and there is no point to drag that issue into HTML at all.

I don't think it is a minor issue at all. My biggest complaint with flash has been the security vulnerabilities, and I trust Google/Mozilla with web encryption WAY more than I do Adobe. Can you explain why you consider it to be such a minor issue?

I don't really understand why you at the same time ready to trust some balck box DRM code from Netflix or whoever. Which can do anything of this sort: https://en.wikipedia.org/wiki/Sony_BMG_copy_protection_rootk...