I'd agree, but licensed content can be revoked - MS is pretty good at publishing digests of "known-compromised" ID's/Serials/Private Keys. I'd be more concerne

I'd agree, but licensed content can be revoked - MS is pretty good at publishing digests of "known-compromised" ID's/Serials/Private Keys. I'd be more concerned about any other, more important facets of a user's account/assets/property that assumes the DRM is secure, and leans on that.