As far as I am aware new EASA regulation that is yet to come in place states that there will no longer be a CAT A or CAT B AOC there will only be a Cargo AOC or a PAX AOC or a Mixed Cargo/PAX AOC.
But nothing concerning the number of minimum Aircraft to have in a fleet, but new financial regulations will take effect along with the above so as to make sure no chabby operators survive which is a good thing in a way and bad in others.
The above info about Above regulatory change came to me from AENA in Madrid.
WA