Roberto Orci has said that though Nero created an entirely new timeline when he arrived in the 23rd century on the Narada, the original universe of ENT/TOS/TNG/DS9/VOY still exists. Unfortunately, when considering everything that Trek has said about time travel in prior films and series, this doesn't really work. Watch "The City on the Edge of Forever." Watch Star Trek: First Contact. Watch DS9's "Past Tense." Watch the whole Temporal Cold War saga in ENT. There are other examples, but in all those I can think of, it was repeatedly stated that travelling into the past and altering events does not cause the existing universe to give birth to new ones, but changes that universe. Using this system of logic, the old universe can no longer exist; the new version is that same reality, only altered. Orci has also cited the TNG episode "Parallels" for why the new universe and the old one can coexist. But the multiple alternate realities seen in that episode had nothing to do with time travel, they were ALWAYS different from the "prime" reality. The only way the original timeline could still exist is if the new one was NOT created by Nero and Spock Prime.