Well, now that the Golden Age issue has come out we know more details about "the Thirteen" who have been retconned into Golden Age history ("reinserted" as they put it, in-universe), so I'm going to do a brief follow up to my earlier post on the subject.
First and foremost, I want to correct the headlines (because I'm Comic Book Guy) that say these are "thirteen new characters". They are not. It's, at most, ten and a half.
The Golden Age Mister Miracle and the Golden Age Aquaman are pre-existing characters. And despite the change in names, "Quiz Kid" is, as I suspected, quite clearly modeled on pre-existing Golden Age character Genius Jones. So, that's a half.
As for the mysterious "Legionnaire"...well, we don't know who that is, yet, do we? However, there is a Time Bubble in the image, from which we can deduce that this boy (the silhouette is a male figure) originates from 31st Century. There's little point in having a representative from the future if it's somewhere we don't already know so... I suggest that it's almost certainly a pre-existing Legionnaire, meaning it's only NINE and half new characters.
Who is that pre-existing Legionnaire? The way I see, there are only four possibilities.
Ultra-boy, because he first appeared on a visit to the past. His power set makes him an ideal Superboy/man stand-in. The exact same rationale applies to Mon-El, or, of course, Superboy himself.
|There's no cape.
|I will admit the silhouette is NOT AT ALL consistently with KK's classically stupid costume, but they could take the opportunity to change it, since that would be a dead giveaway.
|For those of you who watched the show Westworld: Geoff Johns is not Head of Narrative Lee Sizemore, writing stories for guests; he is Westworld Founder Dr. Robert Ford, building a world and hosts that can outlive those stories and guests.
Betsy Ross & Molly Pitcher. A matched set of female sidekicks for Miss America (one of DC's yardsale heroes), who plenty of modern readers have never even heard of, but who's probably going to be reintroduced as a Golden Age Wonder Woman analog. Even though Wonder Woman is STRONGLY name-dropped as being a long-term member of the JSA in Golden Age, so... go figure.
Salem, the Witch Girl. Borrowing a Kirby concept to make a kid sidekick for Dr. Fate, something no sane person would ever contemplate.
|Nabu? Not really good with kids.
John Henry, Jr. A legacy for a non-existent "John Henry" line of heroes that modern day Steel can be the inheritor of, tying John & Natasha Irons to a Golden Age history even if that undercuts the whole 'inspired by Superman' origin. Oh, well.
The Boom. If the Wests and Allens have legacy, then sure as shootin' GJ is going to make sure the Garricks do. It's okay; the name sells it.
Cherry Bomb. As mentioned in my previous post, the idea of giving THE HUMAN BOMB a kid sidekick would be hilarious absurd...if it weren't for the previous existence of TNT and Dan The Dyna-Mite.
The Golden Age Red Lantern and The Harlequin's Son are obviously are about fluffing out Alan Scott's dynasty so that's as overgrown as the modern Green Lantern's.
Ladybug. She's the key to my guess. Ladybug is a kid sidekick for ... The Red Bee. Now... I love the Red Bee. I've spent time imagining treatments for updating the Red Bee. How can you not love a concept as comic booky as the Red Bee? But he hasn't been on the radar for decades and no one's been clamoring for his return; The Red Bee is usually just a punchline or a trivium. So why give Red Bee, of all people, a retconned kid sidekick?
Because Ladybug can shrink. Just like Bumblebee. The existence of Ladybug can be used to link Bumblebee, the Red Bee, the Golden Age Atom and the Modern Atoms (oh, and that idiot, Atom Smasher). Finally, GJ will have that Ant-Man/Wasp Dynasty DC fumbled on creating with all its shrinking/growing characters.
What does any of this have to do with The Legionnaire? Maybe nothing.
Unless the Legionnaire is Gim "Colossal Boy" Allon.