Back in 1980 Cary Bates wrote a comic book story about Superman in the year 2020 that appeared as a backup story in “Superman #354”.
Released on September 11, 1980, the backup story in “Superman #354” (which had a December 1980 cover date) was titled “The Debut of Superman III!” and told the story of the first two Supermen (the original Superman and his son Superman II) heading to the 21st century to ceremoniously pass on the “S” shield to Superman III, grandson of the original Superman. In the story Superman III “kills off” his secret identity in favor of adopting several other secret identities, but a racist group plans to destroy all three Supermen and the floating city of New Metropolis.
The adventure would continue in the story titled “The Destruction of New Metropolis!” appearing as the backup story in “Superman #355” (cover date of January 1981) where Superman III is captured by the racist “Purists”, but manages to signal his whereabouts to the first two Supermen. Superman III alerts his father and grandfather of the bomb hidden in New Metropolis and then captures the bombers.
Both issues were drawn by Curt Swan with inks by Frank Chiaramonte.