You don't come back as white walkers... you come back as wights...
as for the AA comment... are you referencing The Hound?
No although the Hound is my dark horse candidate. The mystery surrounding John Snow's parents also makes him my second candidate.
But this is what I think
The prophecy as Melisandre puts it is "“When the red star bleeds and the darkness gathers, Azor Ahai shall be born again amidst smoke and salt."
I think many readers read "born again" then think reborn, and equate that somehow with death. So when the prophecy says that Azor Ahai shall be born again, I don't think that it means someone has to die and be reborn. But in reality, someone only has to be born. So instead of focusing on deaths, I was thinking about births.
That is why i think John Snow and the smoke rising from his wounds and the salt from Bowen Marsh's tears are just a misdirection. It is just steam from his wounds and tears of sadness. And also it is a death, not a birth. But again John Snow is my second candidate so maybe it is the prophecy.
The first part of the prophecy "when the red star bleeds and darkness gathers", most people equate this with an event that has yet to come or is in the process of happening. But perhaps it is an event that has already taken place. Perhaps the event is a weather related event. Ancient times used stars to try and predict the weather and some ancient communities also thought weather events were caused by the stars and planets themselves. And of course "darkness gathering" could easily be construed as a reference to the darkness of a weather event.
Now the second part "Azor Ahai shall be born again amidst smoke and salt". I think this is a place not a metaphor. And there is one place in particular that fits that description. Dragonstone. Dragonstone is a volcanic island off of Blackwater Bay. It has the smoke of it's volcanoes and the salt of the sea.
That is why I think the Prince that was Promised isn't a prince but a princess.
Daenerys "Stormborn" Targaryen got that nickname because she was born during a great storm and was born on Dragonstone.
I think Azor Ahai has already been reborn, she just doesn't realize it yet.
Maester Aemon thinks he figured it out. This is what he said to Sam in AFFC:
No one ever looked for a girl..It was a prince that was promised, not a princess. Rhaegar I thought … the smoke was from the fire that devoured Summerhall on the day of his birth, the salt from the tears shed for those who died. He shared my belief when he was young, but later he became persuaded that it was his own son who fulfilled the prophecy, for a comet had been seen above King’s Landing on the night Aegon was conceived, and Rhaegar was certain the bleeding star had to be a comet.
What fools we were, who thought ourselves so wise! The error crept in from the translation. Dragons are neither male nor female, Barth saw the truth of that, but now one and now the other, as changeable as flame.
The language misled us all for a thousand years.
Daenerys is the one, born amidst salt and smoke. The dragons prove it.
I think he is right, but RR Martin is pretty clever and it may be too obvious and the reveal not climatic enough.
RR Martin always trying to surprise his readers is why I think the Hound is the dark horse.
Also Aemon said before he died that the dragon must have three heads, so I imagine there will be more to this prophecy than we know now.