Didn't they just try that with Donna Troy?
I don't get why anyone thinks Supergirl makes Powergirl redundant. Similar origins or powers doesn't mean much. They're very different in terms of personality and experiences. Who knows what's even canon anymore, but Powergirl has more of a history with the JLI and those heroes than with the Superman family - she's barely been part of that family of heroes post-crisis anyway.
But in this case it are different incarnations of the same character, and the general rule in post crisis seems to have been that only one version could survive.
I Supergirl had survived her history would have been pretty straight forward.
Havig Powergirl survive with changed origins, and then introduce several differnt new Supergirl versions created imo continuity snarl on a level close to Donna Troy and Hawkman.
The only problem that Power-Girl has had is that DC is chronically indecisive when it comes to its Earth-2 characters.
If general audiences were able to wrap their minds around Spider-Verse, then having two cousins of Superman running around the DCU isn't that confusing.
But if one is suddenly of atlantean origin, and the other is what ever Matrix-Supergirl was or an angle, it becomes really confusing if you don't follow the Supergirl Comics and one of them suddenly pops up in a comic you read...
I mean they went eventually back to both of them being cousins of Superman and one being from different earth at some point in the 2000s, but reading comics from the era between COIE and that point is for casual readers really confusing.
That didn't happen because Power Girl was alive. It happened because DC wanted to keep the Supergirl brand but didn't want their to be any Kryptonians other than Superman. You're looking at end results rather than the actual cause of the problem.
Then do what people do with bad stories; ignore them. None of the replacement Supergirls are even around anymore and most people didn't seem to like Kara being a Kryptonian.
The problem is with DC not knowing what to do with Earth-2 and the JSA. Tying her character to those properties has been difficult for her because DC doesn't really know how they want to use those properties. What exactly are they now? Do versions of the JSA exist on the main Earth or are they just from Earth-2? Is Earth-2 the classic Golden Age universe with older heroes, some pre-Crisis amalgamation of that, or is the New 52 Earth-2 still a factor? Which version is Power Girl from? Did she arrive from her Earth to the main Earth because of Crisis or some other reason if that is no longer canon? There are all these complications that make it difficult for her character to gain any traction.
The base idea of an alternate universe Supergirl who is older and stuck on the main Earth is fine. She is an adult, goes by Power Girl, has shorter hair, and a different figure and personality to the main Earth Supergirl where they shouldn't really step on each other's toes, but then all of her main connections are still to the Earth-2 and JSA characters. She doesn't really have any deep connection to the main universe Superman, Supergirl, or any other main universe characters. So she is stuck on her own and no one knows how she fits in.
If DC wants to keep Supergirl as a teen then I would try and have Power Girl connect with Dick Grayson's generation as they don't have a Superman character in it. So there is a clear opening. They are all adults in their mid to late 20s so that is her age range. It isn't perfect given how mistreated Dick's gen is, but for her character to gain some footing on the main Earth she needs to have those connections beyond the JSA. Like her connection to Harley Quinn from Conner and Palmiotti has been the only thing keeping her appearing in books the last 4 years. It's an example of why those main Earth connections are important for a character like her if she is to remain on the main Earth.
But what would that get her? Another chance to cry like Johns made her do all the time? That's very unlike the classic character. And in any event, as I've said, they've never done a thing with that. And given that other character travel the multiverse, what's the point of having her do that? It seems a bit thin to hang a character on to me. You'd have to give her another niche to go along with that, and if that's the case, why bother?
To me there's no confusion at all. She's an older Supergirl from a parallel Earth (and should stay that way), the atlantean heritage mistake was retconed in a JSA book where Arion revealed it was a lie to protect her.
She belongs to JSA because it's where she feels more at home, close to her Earth-2 memories. She could function as a sort of mentor to Supergirl.
As I said in the Powergirl thread in the Superman forum, I think she should have been a Daxamite and had the lead weakness cured by magic. Almost the way the Legion solved the Supergirl problem by creating Laurel Gand aka Andromeda. Laurel could have even been her descendant. That way Karen (Kara) could have keep all of her powers and her alien roots and let Superman still be the last Krytonian until Supergirl eventually made her re-debut.
That was all made moot when all her pre-crisis history was back during Infinite Crisis.
That would be a great excuse for DC to marginalize PG even more than they have. Daxamites, PG herself had a comment about them in a comic from back in the Atlantean day. "Budget Supermen" I believe is what she called them. She's got to retain a strong connection to a Superman. Which Superman probably doesn't matter as much as some connection, probably familial. All the Superman Family, and PG is one, if not often mentioned as such, depend on their relationship with Superman as a selling point. Besides, she was Kryptonian from day one, changing that part wouldn't help much IMO.
To me that dig was just DC way of trying to make Superman special when they had a whole planet out there with Superman level people with a stupid lead weakness. And I only thought about making her a Daxamite because it was years when she didn't know who she was or where she came from before they added that stupid Atlantis recon on her. And that was only if DC was going to stick with "there is only one universe" where Superman is the last son of Krypton and if or when they would possibly bring Supergirl back so they wouldn't be the same person from separate realities.
Plus she could still be a Super-character. Just have Clark find her crashed ship the same way he found Mon-El back in the 60's but instead sticking her in the Phantom Zone, he could have his JLA friends find her a cure -- maybe Atom and Zatanna could have done a science/magic combo.
That could have led to an interesting story during Invasion when the Daxamites came, testing her loyalties. Of course she would choose her new home here on Earth. But it would have been a good character study.
But like I said, it's all moot because there is a multiverse again and she's back to being Superman's cousin.