It is naive to expect that decrypted media stream will ever be leaving CDM module as so optimistically shown on that illustration.
Microsoft dropped and neglected a bunch of great features when shipping Vista, but it went out of its way to drag Protected Media Path into it. PMP is fronting a major industry effort to create trusted software and hardware framework that on one end accepts encrypted stream and on other draws video pixels on the screen, all the while showing a middle finger instead of raw data to the user on whose system this whole circus unfolds.
It will be laughable to think that CDM won't be PMP-based. Getting access to the raw data with CDM in picture is a pipe dream. Mozilla, sandbox, open source - no matter. CDM exists to prevent raw data leaks.