I saw the interview with Greg Brooks talking about the Queen archives and how there are 16 versions of The Prophet Song. This gave me an idea.
What if Queen were to release an album containing alternate recording/versions of various album tracks from their 15 releases. Something like:
1. Alternate Procession
2. Alternate Death On Two Legs
3. Alternate Prophet Song(like take 8 for instance)
4. Freddie vocal version of '39
5. Some old track they never released
6. Queen version of Man Made Paradise
I'm making this up, but I'll bet that there are some tracks different enough to warrant a release, and that they could release them in this form as if it were an album made for release.
Maybe i'm dreaming, but if this were possible, this would give us fans one hell of a treat.