This seems unlikely, and in fact, Firefox has been moving in the opposite direction with other binary components (Flash, Java, Silverlight). Newer builds of Firefox require you to explicitly confirm that you'd like to allow <site> to execute plugin code. I doubt this will change any time soon.
I'd rather have a (albeit stupid) DRM executable that only performs encryption/decryption than Flash, Java, or Silverlight, which are the current solutions for this. All three of these offer APIs for doing things other than decrypting DRM content, and these APIs have been proven time and time again to be vulnerable to attack, no matter how much time is spent trying to sandbox them properly.
I'd rather have a (albeit stupid) DRM executable that only performs encryption/decryption than Flash, Java, or Silverlight, which are the current solutions for this. All three of these offer APIs for doing things other than decrypting DRM content, and these APIs have been proven time and time again to be vulnerable to attack, no matter how much time is spent trying to sandbox them properly.