I'll believe it when I see it on the shelf. Till then, I believe this just as much as the blurb at the end of
A Feast for Crows in which he said
A Dance with Dragons was half done and would be along the next year (2006).
Even more frustrating is that
A Dance with Dragons isn't the end, there's two more books planned. Maybe the series will be finished around the year 2035. Or maybe we'll still be reading about football and ASOIAF merchandise...