It looks to me as if after a reasonable amount of time has passed (as little as a couple of years, maybe), since the issuance of material in one format, there's room in the marketplace fot the same stuff in another. Essentials and Masterworks seem to coexist quite well--there's no reason to think that color and b&w trades or Showcases and Archives wouldn't.
Life'll kill ya
--Warren Zevon