I am unsure if EEE and EEI (which were issued for motorcycles anyway) will be omitted due to obvious reasons, but EEY and EEO are unused yet besides, but according to the Wikipedia article for plates, it says that the planned future code for Edessa will be MM.
Of course, EEE and EEI are omitted as they were printed on red plates. The next codes will EEO and EEY and then MMA. Motorcycle must be at MMB currently