During Barry’s run to fix things he has to cut off his past self, but once he does and he goes to reenter the time stream he sees three timelines. A female voice speaks to him and explains that the history of heroes was shattered into three a long time ago, but now they must merge back together to save everyone.
I mean, it’s not perfectly explained, but it does make it into an ongoing plot going forward….potentially. A threat so massive it required the DCU to merge with Wildstorm and Vertigo to be strong enough to stop it.