This is from TVTome's Sailor Moon Live Action site:
March 06, 2004:
As Season One comes near its half way point casting director (Katou Naoji and Watanabe Tetsuya ) have started the hunt for actors and actress to play the Black Moon Clain, Chibiusa(if not already chosen) and Sailor Pluto(We are hoping she is given a large part like the MANGA). A cast list of new characters will be given out when Season One draws near.
So what this all really means is... Sailor Moon is being renewed for another season: Sailor Moon Black Moon Arc aka R.