I bought a documentary on the history of DC comics, and watching it, it says that comics had trouble after WW2. During the war, the superheroes had gone to war, and were doing things like fighting the Japanese and delivering rifles and supplies to troops in the European theatre, but after the war, they were so associated with the war and it was hard for the audience to see them fighting criminals and mobsters, and so sale sank. As a result, only Batman and Robin, Superman and Wonder Woman stayed around, with any other heroes that survived being ones that were just in the background of those comics, and those heroes were retooled for the conservative 50s. Strong women like Wonder Woman and Lois Lane became bumbling damsels, with Wonder Woman became worried about her boyfriend instead of being the strong Amazon, and Lois Lane going from tenacious reporter to worried about winning Superman's love and if Clark was Superman, and Superman became a dad. Then came "Seduction of the Innocent" and the witch hunts where comics were said to be destroying the youth of America, which had a devastating effect on the industry and drove parents to keep comics out of their homes and drove out of business all sorts of horror comics and other comics that were viewed as juvenile. In response to that, the Comics Code Authority was created, and there was a self censorship of the industry, and they neutered themselves and self regulated themselves, leading to things like Pat Boone comics about the life of singer Pat Boone, and it just drove away the youth. Just one year after the Comics Code's implementation, comic sales dropped by 75 percent, and it appeared that comics, at least super hero comics, were going to die out very, very soon.
What saved Comics was the Silver age. DC revitalized itself by putting Julius Schawtz in charge of DC's plan to bring back the Flash, which he did. Instead of redoing the old Flash, he did a Flash for the times, who was transformed into a man capable of super speed by science, and who worn not the original Flash's hokey outfit, nor any reimagining of it, but a sleek suit design never before seen. And then Schwartz oversaw a series of reboots where other heroes were brought back with modern, serious, science based origins like Green Lantern and Martian Manhunter, and he oversaw the creation of the Justice League, which used the earlier concept of the Justice Society, but gave it the new heroes and a new name as the other one was dated.
The Justice Society lead the president of Marvel to have Stan Lee create the Fantastic Four, which lead to the beginning of Marvel's greatness. So Schwartz and the Silver age basically saved DC as well as Marvel.
But what if that didn't happen? What if for whatever stroke of fate, that revival didn't kick off? Perhaps DC tries in an alternate scenario to reboot the past heroes in a goofy way which doesn't find an audience and none of the revival happens and super hero comics die off; I wouldn't put it past DC since in the 60s, when Marvel was dealing with 2-dimensional characters, DC was till in the 50s and was far behind Marvel in sale. What if comic books died off by the 1960s?
Bear in mind, comic books in the 60s and into the 70s had an impact, and gradually reflected serious things like racism, drugs, political corruption, and all the stuff going on at the time and the seriousness that was of the times. Christ, to college students, their revolutionary heroes were not only Malcolm X and Che Guevara, but also the Hulk and Spiderman. So that's not there. And you don't have comics taking on a sense of seriousness and maturity and self examination.