Trilogies: Final Year?

Certain DC comics are classics, including these three "trilogies" (I am calling them that but they do fit together, as I will show):

The Man Of Tomorrow by Alan Moore;
The Man Of Steel by John Byrne;
Lex Luthor: The Unauthorized Biography by James D Hudnall.

Batman: Year One by Frank Miller;
The Killing Joke by Alan Moore;
The Dark Knight Returns by Frank Miller.

The Longbow Hunters by Mike Grell;
Green Arrow: Year One (GAY1) by Andy Diggle;
Batman: Rules Of Engagement by Andy Diggle.

(By The Man Of Tomorrow, I mean a collection of Alan Moore's three Superman stories, which include a two parter. Titan Books collected them under this title albeit in black and white.)

The common themes here are high quality writing and art, beginnings and endings:

Moore concludes and Byrne re-creates Superman;
Hudnall writes the origin of the new Luthor;
thus, an end for Superman followed by new beginnings for him and his main opponent.

Miller begins and ends a new Batman;
Moore rewrites the origin of the Joker;
thus, new beginnings and an end for the Batman and his main opponent.

Grell presents a mid-life crisis for the then current Green Arrow and slightly revises his origin;
Diggle presents the origins of a new Green Arrow, the Batplane and Wayne Charities;
thus, a middle age, a retold beginning and a new beginning for Green Arrow and some beginnings for the Batman.

These lists refer to three continuities:

the first began with Action Comics no 1, June 1938, and ended with Whatever Happened To The Man Of Tomorrow?, 1986;

the second began with The Man Of Steel and Batman: Year One and ended with The Dark Knight Returns;

the third began with GAY1 (many other works are involved but here I highlight a few peaks of quality).

Byrne's Superman, Grell's Green Arrow and the Joker come together with Miller's Batman and Selina Kyle in The Dark Knight Returns. Mindy Newell's Catwoman miniseries continued the character of Selina directly from Batman: Year One.

Since Batman: Year One begins the Batman's career and since The Dark Knight Returns describes his return from a ten year retirement, it has been suggested that Miller could also have written a Batman: The Final Year, describing the build up to retirement.

This would have disclosed events only hinted at, like what had happened (something bad) to Jason, the second Robin. In later comics set in current continuity, the Joker brutally murdered Jason but there is no hint in Miller's story that whatever had happened to Jason had been done by the Joker. Also, whatever it was had caused the Batman to cover it up, then retire, while superhero activity was governmentally banned or covered up as in Watchmen, but this did not happen in continuity, except for the temporary superhero ban in Legends, so there is still a different story to be told here. The Dark Knight Returns, no longer a possible future, becomes an alternative timeline.