This feature is called "I Tell You What If," and it is about all the times that an alternate reality storyline ended up becoming part of official continuity. Very often, if an idea being good enough to be used in an alternate timeline it will often end up being considered good enough to use in the REAL timeline.
Today, we look at how Robin's Batcave memorial predated his actual death!
You don't need this column to tell you that Batman: The Dark Knight (now best known as Batman: The Dark Knight Returns, which was the name of the first of the four books in the series) was an incredibly influential comic book series. Frank Miller and Klaus Janson's tale of Batman returning to crimefighting after a decade-long absence and the impact that he has upon a new and drastically changing world was a brilliant series and it became "the" take on the character for generations of writers to come. Nearly every Batman movie since that book came out has used Miller's vision of Batman as the basis for their own, from Tim Burton to Christopher Nolan to Zack Snyder (Snyder would often adapt full sequences from The Dark Knight into his take on Batman).
That influence was obviously also felt in the world of comic book writers, as well. One of the writers who was most influenced by Miller's series was Jim Starlin, who had been brought aboard as the writer on the main Batman series following Max Allan Collins' brief stint as the writer on the series following Miller's "Year One" alteration of Batman's origin following Crisis on Infinite Earths. Collins' take on Batman was to make the series a compelling all-ages title, while Starlin was more influenced by the darker side of Miller's take on Batman.
The Miller influence was evident in Starlin's first story on Batman, one of the first "miniseries within a series" comic books, as "Ten Nights of the Beast" had distinct cover formats to make it seem like it was its own series. It was a political thriller that ended with Batman leaving the main villain to starve to death as he was too much for Batman to handle otherwise.
In any event, during Batman: The Dark Knight, Miller was silent as to the fates of both Jason Todd and Dick Grayson, but when Carrie Kelley saves Batman's life during his one-on-one battle with the leader of the Mutants gang, she takes him back to the Batcave and she discovers a memorial for Robin...
Note that this was 1986 and Batman had not even been rebooted yet. Jason Todd was still a complete knockoff of Dick Grayson. Soon after, Collins would introduce Jason's new origin as a kid from the streets who met Batman after trying to steal the Batmobile's tires. So having a memorial like this was strictly a "Oh, it's just an alternate future" thing, as there were no plans to kill off Robin at the time.
Of course, let us stress "at the time"...