Just had myself a theory come to mind .. so here goes ..
In "Time of Angels" they read a lot from this book about the Weeping Angels. Most of it seemed instructions for the story at hand however one in particular wasn't used in the story and seemed at the time to be a season-long clue:- "What if we had ideas that could think for themselves? What if one day our dreams no longer needed us? When these things occur and are held to be true, the time will be upon us: The Time of Angels."
As a clue it isn't much but it does speak about dreams becoming events in the manifest reality.
Next, in "Amy's Choice" we had the cast spending the whole episode in dream worlds. Duh. The two dreams, one was Amy's and the other was the Doctors, both ended in the destruction of the thing or person they most held dear. For Amy that was the dream-world Death of Rory, and for the Doctor he chose to blow up the TARDIS.
In order to escape the dream world one has to destroy the thing keeping them in the dream?
Anyway here's the theory. What if one day our dreams no longer needed us? Meaning, what if one day our dreams could live on their own without our dreaming the dream? We saw into the Doctors' and Amys' dreams, and in the end of this episode we saw evidence of both the dreams existing in the manifest reality. Meaning the TARDIS blows up because it's an event from the Doctors' dreams and is for some reason due to become manifest reality. Likewise we saw Rory die because it was an event in Amys' dreams.
Unless this is the season-long dream of a lonely Doctor with no friends who's dreaming what it would be like to have real friends.