Cable died during Second Coming. He sacrificed himself for the cause of saving the mutant messiah, Hope, who he raised and taught how to survive. Cable's life has never been easy as he was infected with the techno-organic virus as an infant. Being swept away to the future by the Clan Askani in order to ensure his survival, he's fought battle after battle against Apocalypse and others. When he finally revealed himself in the present, he continued his crusade against the forces of evil.
Cable has been a soldier his entire life and scarifying himself was an easy decision to make. Because we're talking about a comic book death and because he is part of the X-Men, dying is something that can be easily overcome. It has been officially announced that Cable will be returning, or be reborn, in December when Jeph Loeb and Ed McGuinness take on the task of bringing him back.
With deceased characters in comics constantly being resurrected, it shouldn't be too difficult to come up with a plausible way for Cable to return to the X-Men. Because fans can be extremely vocal and hard to please, care and consideration has to be made in order to make the return worthy and not diminish the sacrifice he made a year ago. Thus the question remains, how exactly will Cable be reborn?
== TEASER ==
When Cable died bringing the X-Force team back from the future, we only saw his death from the present. We can't be exactly sure what it was like on the other end, in the future. It appears he became completely engulfed by the T-O virus but what exactly does that mean? With the explosion that occurred, perhaps something was able to knock the virus into remission. Sure the explosion looks pretty gnarly but what if it was just a T-O virus shell on top of him that actually blew off of him?
For all we know, Cable could have actually survived his death. Because it was supposed to be a one-way trip, he could have been spending all these months in the future trying to figure out a way to return to the present. Being in the future gives him access to future technology (naturally). Since he as spent so much time time-traveling, he knows how time-traveling devices should work. When he is finally able to cobble together everything he needs to make a functioning time-travel device. He'll come back and everything will be back to normal. How many months or years it would take him is another issue.
But that'd be too easy.
Cable has spent a lifetime in the future. His entire life history hasn't been chronicled or revealed. With all the time travel he's done, who's to say that he didn't journey to the (current) present the few years before New Mutants #87, where he was the leader of the mercenary team, Six Pack?
What if he traveled back when he was younger, like in his twenties? With time travel and knowledge of future events, he would know that revealing too much to others about their histories could be hazardous. The Cable we know could have been aware of all the events that will occur after his REBORN series returns him to the present. It's also possible that at the end of this journey in his younger days, something happens that caused some minor amnesia. Maybe he even had a telepath make some adjustments to his memories when he returns to the future in order to live the rest of his life without putting risk to the timeline.
With his return falling under the REBORN title, that's another angle that should be considered. Captain America: Reborn didn't deal with Steve Rogers actually being physically reborn. It was simply a metaphor for bringing him back from what appeared to be his death, when he was actually trapped bouncing around time. With Cable, we could have the same thing. The use of reborn could simply mean a way to return him to today's comics or it could mean he's actually being reborn.
We need to keep in mind who his true mother was, Madelyne Pryor. She was a clone of Jean Grey but what if some elements of the Phoenix Force resides in his DNA. Could it be possible that Cable will be reborn but won't be the same Cable we know? He could physically resemble the character but if he doesn't retain our Cable's memories, it would bring a whole new twist to the idea of a character returning from the dead.
But this wouldn't exactly explain why the teaser image shows him with the same metal arm. Although it does appear that his arm was in one piece when he exploded. For all we know, there could be some other person that knows of the history of the man called Cable. What if he happened to be one-armed himself or somehow was able to modify Cable's arm to take over his mission after being inspired by his tales?
We'll have to wait a few months before we get more detail. For now, we can just hope that Cable being reborn doesn't mean we'll see Baby Cable again...