The character diversity in Astro City largely follows that of Real Life comic book history, so this trope is played straight deliberately.
As seen in flashbacks, Cleopatra started off as a blonde Caucasian woman. By the time the series begins, however, she has been replaced by a dark-skinned woman.
The original Quarrel was a male criminal. He is succeed by his daughter, who took his name and gear to build a heroic legacy.
Little is known about the original Flying Fox other than he was male. The second Flying Fox is the daughter of a state Senator, and a lesbian in her private life.
The original Goldenglove was a male super-criminal. His daughter dons the identity of Goldenglove II to be a master thief, but is eventually swayed into being a hero.
Stray I was a male member of the Astro City Irregulars, while Stray II is a female free agent who was sometimes seen with the Confessor.
Women have donned the mantle of The Phantom, though so far only temporarily (the oath made by the Phantoms specifies "sons"). The 21st and current Phantom's children consists of twins, a boy and a girl, and should he ever kick the bucket (yeah, right) it has been implied that the two of them might end up sharing the duties of the Phantom.
Temporary mantle-holding has also been done by black men, such as Emperor Joonkar. This was handwaved by other characters' superstition, stating that if the Phantom wants to present as black he probably has a good reason.
In Dynamite's King Features comics, Mandrake the Magician's ally Lothar takes up the mantle of the Phantom while seeking the Phantom family's heir, becoming the first non-temporary black Phantom. (The last of the Phantom family died with his heir missing. Lothar's predecessor couldn't find the heir, so he took on the Phantom mantle, and before he died, he asked Lothar to find the heir. Believing the world still needed a Phantom while he searched, Lothar decided to take on the name.) The actual heir to the Phantom legacy turns out to be a woman, Jen Harris.
The original Fighting Yank eventually died, and his daughter Carol decided to carry on his legacy as the Fighting Spirit. In addition to being a woman (the original Fighting Yank was obviously a man), Carol was eventually revealed to be a lesbian as well, making her a twofer.
During a period where Mark Grayson was unable to fulfill his duties, he was replaced in the Invincible role by his buddy Zandale Randolph. As Invincibledeconstructs a number of superhero elements, replacing Mark with a black dude was likely an intentional invocation of this trope.
The Golden Age hero American Crusader was a white man. His modern-day successor in the Project Superpowers universe is a black man.
In 2000 AD, the character of Sam Slade, Robo-Hunter, was succeeded by his granddaughter, Samantha Slade.
The Witchblade franchise would count, since the main story revolves around an Italian-American cop named Sara Pezzini. According to Word of God, the Witchblade anime, the Witchblade Takeru manga, and the novel Witchblade: Ao no Shōjo are all considered canon in the Top Cow universe, making these an example since the three protagonists (Masane Amaha, Takeru Ibaraki, and Yuri Miyazono) are all Japanese.
Sara was also briefly replaced by Danielle Baptiste, a young bisexual woman.
The Shield originally was a man named Joe Higgins. When the comic was rebooted in 1959, the main character was changed to a man named Lancelot Strong. Later on the character changed again to Michael Barnes. The 2015 reboot stars a woman named Victoria Adams.
When Rebellion brought back many of the old IPC/Fleetway characters in Scream! and MistyHalloween Special 2017 and the following year's team book The Vigilant, it's revealed that Dr Sin, the Occult Detective from the early 2000 AD strip of the same name, has died, and has passed his mission on to his grandson, a black British hip-hop artist who calls himself Sin Tax. And Thunderbolt the Avenger from Buster (aka PC Mick Riley) has also died, passing his Transformation Trinket on to a female colleague, Mary Landson.
