The idea of a multiverse and a multiversal crossover to give meta commentary on the state of the industry and on the current events in comics is not just something Grant Morrison does.
In late 1996 Image published Shattered Image, a four-issue miniseries crossover event.
Okay I didn't have time to actually get into it this morning - I still kinda don't - but I want to take a moment out of my schedule to talk a little bit about retcons. This is a vast topic and I have an (unfinished) damn essay partially written on it so this will just be brief.π§΅