There isn't enough of a demand for Bitcoin Collectibles outside of physical coins/notes for it to warrant it being split into two separate sub-boards. All that would likely happen is the activity from the Collectibles sub-board would move to this new one, leaving the Collectibles sub-board essentially dead.
Maybe a physical coin section with an auction subtopic?
IMO, the opposite should happen. I think that creating a Physical Coins sub-board in the Auctions board would be a better way to combat the messiness of Auctions currently, than killing a current sub-board to achieve it.