Ice dragon = The Long Night

[King Adrian Storm]

What if the Ice Dragon isn't a literal dragon, but a "term" for the long night? I don't know if this is a theory or not, but I wanted to hear your thoughts. I don't see there being a literal ice dragon in the story I think the Others are the "Ice" and the dragons are the "fire". I think in the stories that were passed down people associated the long night with something dangerous and deadly, and since in Essos there were literal dragons, maybe their stories were mixed together. IMO the Ice dragon breathing ice and a chill that can freeze a man solid is supposed to represent the terrible snows. I think the wings being translucent is a hint that it could be fake.

[Son of Man]

The ice dragon is a star pattern in the sky.  As seen from the north.  It is not out of the question to have had a large creature made of ice.  Any large creature that flies could be referred to as a dragon.  Whether it shares the same species as the fire dragons or not, to the average people, a sufficiently large creature that flies is a dragon.  So a flying creature that was either the color of ice or was made of ice.  Which will mean the creature was magical. 

[Curled Finger]

Your idea applied to this particular story isn't bad except that Ice Dragons are as legendary as Lann the Clever or any other magical character in story.  I was hoping to pull up the bit where ice dragons melt into hot pools but couldn't find it in the World Book.  Taken directly from TWOAIF without further context your idea works.  However, the legends of the Ice Dragons seem pretty localized to the area near the Shivering Sea whereas the legend of The Long Night seems to be a global event.  Maybe it's attributed to different creatures in different areas and this bit is specific to Westeros. 

Looking at the TWOIAF quotes so recently in light of your idea I can totally see where you reached your conclusion.   I would caution, however, that mythical creatures are a real thing in this world.   Kraken are mentioned in ADWD during a small council meeting, giants have attacked the wall, COTF are babysitting Bran and we almost have POVs from direwolves.   I am of a mind that Ice Dragons were a real thing.  Who knows, they could make an appearance in the books to come?   Maybe even with the Others.   

[Roswell]

Dragon is also a term for a person of power. The one at the top.  This Ice Dragon was somebody who had power over the elements and can do magical things with frozen water.  He brings death to all warm-blooded creatures.  This creature is at the top of the ice food chain.  It is probably Jon Snow.