Honestly, I do believe that she's dead. Her 'humanity' being regained, at least as how I interpret it, is that her soul, spirit, whatever, was released from Lavos' grasp upon her demise, and so she was able to pass as it was meant to be.
This does NOT, I repeat does NOT completely and definitely say she is dead. Had she survived and escaped, I like to think that the possibility of it could be explained with the 'corruption' itself. I, for one, am an avid fan of the Soul series, the Soul Calibur for Dreamcast being my favorite. After Siegfried is finally released from Soul Edge and his Nightmare persona, it still doesn't make him free of the taint of the demonic sword. This is actually mentioned in his storyline in SCIII, where he goes to Kilik to try and learn his techniques for purification. It says that he could never be able to use them due to the fact that Soul Edge had left a lasting impression on him, and therefore he is, obviously, not quite normal/human again, retaining some of the traits from his time as Nightmare. That was corruption by an evil sword; considering how much more power Lavos, who is basically a sentient, parasitic asteroid, has than that measly blade, I would say that the effects contact with it had on Zeal would most definitely linger, and one of those could be the timelessness, and near-immortality she'd attained from her connection would most likely be very diminished but far from completely gone. Perhaps she'd survived because of the residual power she still retained, and was able to drift away to some other place. I find it something fun to toy with that she'd drifted into the End of Time, much like Gaspar, and that eventually she'll make it to the guru's humble abode. After all, time is basically an irrelevant concept to study and watch from that little outpost, as it's just the ether that hangs about the space-time continuum. Were she to live through something like that and make it there, I'm very certain that she would be able to spend what's basically the rest of eternity there with Gaspar and Spekkio.
Of course, in all likelihood this theory is shaky at best, and so I presume that Zeal had officially and irrevocably died after the Omen disintegrated. The biggest reason I find that the most plausible outcome is because that's probably just how Kato had intended it to be, and so until the official word is given, she should be thought of as a dead woman and resting soul. Just my two-cents here.
