Five Years Later
I honestly have no idea how DC expects their new timeline to work without a total reboot of the universe. The idea that super-heroes only appeared five years ago is certainly workable for most characters. There's no difficulty, for instance, in saying that the Flash, Superman, or Wonder Woman only appeared five years ago. It's pretty easy to streamline out most of their histories.
The problem, as usual, is Batman. Batman wouldn't be a problem if DC was really rebooting their universe. But according to DC all the Batman characters are still canonical: Dick Grayson was the first Robin, Jason Todd the second, and so on.
How exactly is that going to work? How are they going to fit all of that into five years? And the problem of Damien just raises further questions.
I don't know if they'll try to come up with a convoluted, not terribly convincing explanation or just go the Infinite Crisis route and hand wave it away with a "Superboy-Prime punched a wall!" Either way, I look forward to seeing the frothing Internet masses explode in rage and indignation.