One question I would have is: what proposals exist or have existed for additional privilege bits? How much pressure is there to use some of the remaining bits? I actually looked into the history of the permission bits and found that we can summarize and approximate the history as 10 years of expansion from 4 to 12, then nothing added in the last 10 years.
I made an argument for an "ANALYZE" grant a little while back, and it kinda leads one to want one for VACUUM as well.
