Well, if DC had cancelled or repurposed Action Comics and Adventure Comics at the same time they had done so to All Star Comics and World's Finest, Superman could have been forcibly benched for a while.
Harder to revive Captain America. When his book was turned into a horror title in 1949, which is usually considered the end of the Golden Age, Steve was still fighting WWII, despite having gone through so many adventures at the time (multi-issue storylines being almost unheard-of in the Golden Age) that the U.S. would have had to have entered the war back when it was started to make them all work chronologically speaking. With VJ Day, it becomes dificult, if not impossible to give him a purpose until Korea and the official start of the Cold War, since he didn't have anything to do with street crime until after the Watergate storylines OTL.
His Fifties Revival is mostly reviled today because it was a way to cash in the House Un-American Activities Committee hearings, and several of the villains were thinly-disquised expies of people brought before it. It's telling that the only reasons Stan Lee could revive the character again in the Sixties are 1, Neither he, nor Jack Kirby, nor Joe Simon had been a part of that publication, and 2, Steve Rogers never showed up in his civillian guise and Bucky was still a teenager, meaning he couldn't have been the Bucky Barnes from the WWII comics.