I am not sure what the point would be of yet another version of Mint based on a different flavour of Linux. Ubuntu and Debian are quite sufficient. Debian is a also great fallback if the Ubuntu guys should go completely off their rocker.
If anybody in the Mint Team wanted to do something truly different, they might consider "Mint FreeBSD Edition"
Having ZFS, jails and the clarity / cleanliness of a BSD base would be awesome.