So, apparently the post-Reboot DCU takes place in a world where Superman, here the first superhero, only started his super-career five years ago. BUT, but all of Geoff Johns and Grant Morrison's recent storylines as well as Big stories from the past like the Killing Joke are still in continuity. All of which took place in the five years since the debut of superheroes.
So the Sinestro Corps War, Batman RIP, Final Crisis, Brightest Day etc. all still happened... all within the same five years.
Blimey, it's suprising that Batman and co. didn't die of exhaustion with all that running around!
Oh, and speaking of Batman, another element of this alleged five year old universe means that Barbara's career as Batgirl, her paralysis, her career as Oracle, her founding of the Birds of Prey and mentorships of Cass, Steph and Misfit all happened in those five years as well.
AND it'd mean that Damian would have to be conceived five years prior to Bruce becoming Batman in order for him to be Robin now, as well as Bruce somehow getting through Dick, Jason, Tim and Steph ALL IN THE SAME GAP AS WELL!
Though that bit could theoretically be "fixed" by Steph flat out not existing any more, the same as the JSA has been erased to "give the title a break", as Didio said, which could explain why she and Cass aren't in any solicits.
Hopefully this isn't true, otherwise this does look like the event's been that well planned.