That's exactly what Flashpoint was, Barry went back in time to save his mother, but in so doing, essentially destroyed the world he loved. He never became the Flash. Bruce Wayne died and his father became a very unsuccessful Batman, etc. Eventually, Barry had to go back and ensure his mother did die so that the intricate chain of events that led to the then DCU would occur. Of course, the same thing will have to happen here, they've built the entire story around Flashpoint from the very first episode, that's why I don't know how they can not have the storyline affect other series like Arrow and Rogues, assuming it's going by the time this story comes to a head.