I believe they've already built in an escape hatch for themselves. And it's on the cover of every one of their new comics: "The New 52."
What does "the new 52" mean? Of course, the name comes form the fact that DC launched 52 titles at once, defining a new DC universe. What are you, Get-a-Life Boy, stupid? Everyone knows what "the new 52" means.
Okay, now let's suppose that one of the new titles gets cancelled.
So why 52? Why wasn't it "the new 42" or "the new 37" or "the new 106"? Okay, comics come out weekly and there are 52 weeks in a year...but why should that be significant? It's not like they're issuing one of these titles each week or something. Was DC so enamored of the weekly 52 series that they want to name their new universe after it?
Here's where the escape hatch comes in. Any time they wish, DC can reveal that "the new 52" is actually the previously-unexplored Earth-52, created (somehow) by the events of Flashpoint. Badda-bing, badda-boom, they can keep the remaining "new 52" titles in print, and bring back the old versions of previous titles.
You read it here first.