Why Game of Thrones and Christopher Nolan's Dark Knight are so popular in 2013
Adam Rifkin stashed this in Game of Thrones!
I think it speaks to the time period of its popularity, so in terms of classic literature, it may one day be held up as a product of the new millennium in fantasy. Of course, ASOIAF started up roughly 20 years ago, and was popular in some circles.
The true explosion of popularity, bringing the series into popular culture, however, came in the post-9/11 world (and with HBO's help), where people (and as an American, I'm looking at it with a particular, biased view, which I should disclose) found themselves at a sudden loss of that comforting notion of clear good and clear bad. The world became a more muddled, dark, and confusing place.
We no longer need to worry about just state actors, but also non-state entities (terrorist organizations).
We now look at our government and our country with pride, but also with a little fear, knowing that some steps it has taken and decisions it has made are less than reputable (not that this wasn't the case before 9/11).
There's a lot of uncertainty and fear among 'the small folk,' of the world. Martin's story has captured our attention because it reflects all this. As Tolkien shined in an era where the people had adapted to, defeated, and understood one great evil, Martin is giving us a fantasy that shows us how our society now views the world - a place where things aren't so cut and dry.
This shift can be seen in a lot of cultural works - an example I point to is Nolan's Batman in comparison to other iterations of the character's story, and how dark it gets in Act 2 and most of Act 3 before our hero succeeds. So I think, one day, the currentpopularity (in terms of pop culture, I guess) of ASOIAF will help influence how it is remembered - as a piece of literature that reflects a general change in worldviews, feelings of security, and redefining of 'bad,' and, 'good,' among other things.