I don't think we'll ever revisit the KC Earth again. At least not in terms of sequels or anything like that. Ross is on the outs with DC and Waid doesn't seem to care much for the story for whatever reason. Neither one seemed able to agree on how it should end and apparently there was a lot of micro-managing by DC at the time about what could and couldn't be included in it. It had to reflect the post-Crisis continuity at the time. So no Barry, no Hal, and it had to include that stupid ponytail.