Anyone taking bets on how long it will be before CDMs start requiring extensions that allow access to platform Output Protection/HDCP mechanisms?

If nothing else, the standard already allows for the CDM to access the network (albeit managed by the user-agent) which means, for example, it could ping Microsoft to ask about this particular Win10 computer (as identified by user agent, IP address, and/or user account data from the content provider).

Netflix/Microsoft/Hollywood/etc. aren't going to stop until they can close the loop as much as possible, with MS and hardware manufacturers already working to tighten things from the other end (see HDCP and the various frameworks for "protected content" that MS has been working towards).

Either providers will push to integrate those platform-level frameworks, or they'll just stop offering content to web browsers entirely.