Untitled Batman Beyond: Return of the Joker sequel

A second Batman Beyond film was planned, but it was cancelled due to the dark tones and controversies surrounding the previous film Batman Beyond: Return of the Joker.

Plot
It involves Terry McGinnis, the Second Batman, discovers that he is a clone of Bruce Wayne, his predecessor, and Selina Kyle, Catwoman, being his creator, but the rest of the details were unknown.

Why It Was Cancelled

 * 1) The film was cancelled following the controversies surrounding Batman Beyond: Return of the Joker (mentioned earlier).

Result

 * The film was permanently cancelled.
 * Some elements of the film were adapted to the Justice League Unlimited episode, Epilogue.