You’d spend years potentially catching up to everything that’s ever included in an editors note. The main things to read would be the major universe impacting story arcs. Things like the various Crisis books, Flashpoint, Blackest Night, Rebirth (The Johns runs of Flash and GL, not the new Rebirth stuff), Zero Hour, and maybe even things like Death of Superman and Knightfall are really the big ones (The Crisis books for sure). I felt the same way at one point. Before I wanted to read Rebirth I wanted to catch up with New 52. I almost spent a year “catching up”. By then I was just behind again. I resolved to read major New 52 story arcs (I had already read the stuff I just mentioned). That got me close enough that I was up to date. And for the most part, aside from the major events, little things like [“Superman is off planet right now” *See Superman issue #267, on sale now!] don’t really matter. A lot of times it’s really just fan nods to say “Hey, remember that!” Don’t get me wrong, you should still seek out these major events, as they have a lot to do with character development and such. But from a standpoint of wanting to be “in the loop”, most evens that have happened more than a decade ago are almost footnotes in modern stories.