Funny, weren't both Captain Boomerang and Colonel Computron trademarks of the Willard Wiggins toy company? The whole point was to spoof the marketing of these toys for kids and the cold-blooded exploitation epitomized by Wiggins. Seems to me that still works. Maybe the problem is later writers have forgotten the satiric purpose of those characters. They are supposed to look corny. Obviously, someone like Digger Harkness would give up the moniker, because it was only invented for him as Wiggins' pitchman. And once he quit that company, he wouldn't even be able to use it without violating his contractual agreement--like the Lone Ranger Clayton Moore not being able to become the Lone Ranger.
I see "out-dated" (not a term I'd use) as a seasoning. Sometimes in a story, you want to use that spice--you want something to have the feel of a bygone era. Heck, look at how many T.V. shows still do a 1940s film noir episode with their characters.
You can just as easily argue that gunslingers from the Old West belong to the past--that doesn't mean they aren't an important symbol that a writer can always employ with great effect. Saying something is "out-dated" is admitting to having no imagination.
Hmm...the characters themselves aren't dated, but Superman's and Batman's sense of fashion feels very, very dated every time artists continue to draw them wearing trunks or bring back the trunks.
Red Rocket, Red Star and every other Russian hero with Soviet symbolism.
They updated KGBeast story to now be a freelance mercenary that has been hired by Penguin or Bane
Kate will keep her DADT backstory now that characters age slowly, in fact, all of them do, and outside of comics it's important because there's a new generation of reader who didn't even know that DADT used to exist
Hal used to be in Korean War? Well the Green Lantern Secret Origin in 2005 never mention that. He's just a test pilot, after being fired from the air force
Rename him Digitron and make him a cyber villain in general
Well... digitron is still a bad name
but they still exist so it's not dated, it's just not as glamorous
Any character who is not a member of any specific culture but adopts their symbols or becomes better than the natives at their own culture, won't be accepted in the current climate.
Any character who fits the Dragon Lady archetype has to be revamped. I think femme fatales are still popular though.
Yeah, where are we getting the idea that circuses are gone!?? They still exist and still travel. They aren't outside in tents around me.. but inside the local sport arena/civic center... but I literally saw trapeze artists 2 years ago. They didn't operate without a net... but then they weren't the flying graysons
As for Hal? There are still jets... Jets still need testing. Test Pilots still exist. Always will. Still requires fearlessness and guts... Hal's Showcase 22 origin story is still 100% legit. Maybe retconning in the military stuff isn't as accurate, but he started as a Test pilot for Ferris... Just keep it simple. And honestly, 'civilian flight/space programs' are only going to get more relevant. Hal's still fine the way he is.
Of the big IP, not counting stuff like General Glory (shameless Caption America pastiche), it may actually be Kamandi.
I like it, but the reverence for Kirby's vision has largely kept it stale for decades. It always feels like a 70s post apocalyptic sci-fi movie. I adore those, but the vibe is 50 years old and I've never seen much done with it that works that isn't just playing the hits, so to speak. Sometimes it gets a very pretty coat of paint, but it's that same story as always. Even the Metal Men resolved the Magnus/Platinum relationship recently.
Of Kirby's successful stuff at DC, I feel like Kamandi just hasn't changed any time we really get to see him. Again, I'm not saying any of it's bad, just that it's been a stale IP at least if my memory serves. I want to stress that I actually enjoyed a lot of Kamandi I read.
Contrast Kamadi with New Gods and what people like Morrison or King get out of there latter whereas the former is always pretty much the same.
Kamandi is like a thing DC has been trying to make happen for fifty years without success.
Buried Alien (The Fastest Post Alive!)
Buried Alien - THE FASTEST POST ALIVE!
First CBR Appearance (Historical): November, 1996
First CBR Appearance (Modern): April, 2014
This is inevitably going to be very subjective.
And I hate to say it, but, like a lot of things in the world today (and especially in the US), a lot of it will come down to one's political inclinations.
I mean, if you look at the world from a left-leaning perspective, then you can argue that a character like Batman is 'outdated'. He's a white male billionaire who spends his nights violently beating up criminals and mental patients with the arms-length support of the local police department. Hell, some would even regard such a character as a villain...
And yet, this 'outdated' character remains the most popular superhero in the world, and the most powerful and viable brand in the genre, in the US and across the globe!
For all the talk about characters created by straight white men from the early part of the 20th century being outdated though, many of these characters have today become even greater worldwide pop-cultural behemoths than they've ever been before! I guess you're talking mainly about comics in your post, but you have to consider that in the larger context, the comics are today just the foundation for multimedia brands - and those brands are thriving like never before, with only superficial updates!
Which is not to say that comics do not need more diversity, or that diverse characters can't be successful. On the Marvel end of things, the success of Black Panther (also a character from the early part of the 20th century, but who's been relatively obscure till recently) has shown the way in that regard. Over at DC, John Stewart, who's seldom been the face of the Green Lantern franchise in the comics, became a breakout hit in the JLU cartoon, become THE GL for a generation of fans, and hopefully will be in any future film adapting the franchise. Black Adam's coming up. And its not just headlinig characters, but diverse supporting characters as well who've gained a lot of traction - Vibe from the Flash TV show for instance.
But the comic-book fandom is a relatively small part of the overall pie. And the portion of the comic-book fandom who worry about the characters being 'outdated' (whether for political reasons or not) is even smaller. Just to put things into perspective...
I'm lifting this directly from a conversation I've had about this, but Kamadi is always about the same kid on the same world that got ruined by the same disaster with the same gun and Thor's same magnificent hair.
Kirby had a solid vision but it feels like the only people who bring Kamandi back are those too in love with it to take a real swing. That doesn't mean they're bad books, but I could never fault someone for saying it feels old.
I think that's the crux of the problem. When Hal was first invented, being a test pilot turned space ranger was the height of cool. Now, not so much. My fondness for the character lies largely because he harkens back to that era. That said, there's certainly an appetite for heroic astronauts, which GL: Earth One was able to mine to great effect. I just think the test pilot angle needs an update to keep the character feeling like he's pushing the envelope. Test pilots aren't really doing that these days.
As for Hal's military service. I don't think just having him serve in the Air Force is enough. Like I mentioned earlier, there's a big difference between being a fighter pilot now and being one during the Korean or Vietnam Wars (which Hal was a veteran of Post-Crisis). I think the character is missing something if he hasn't seen actual combat, which New Frontier was able to explore excellently. Having him flying around in million dollar jets for the world's largest military or do bombing raids on 3rd world countries doesn't really have the same vibe to me.
Superman but its feature not a flaw. A well done Superman feels outdated, other than couple Shonen anime Protagonist they don't build heroes like that anymore. I saw people gushing over the scene in Superman and Lois where he saves the kid from the car and I get why it works but feels alien today as well.