Has the rise of religious ‘nones’ come to an end in the U.S.?

It strikes me that if I believe in perserverance of the saints and eternal security, I don't believe that I should put too much stock in surveys like this. What they're measuring is nominal affiliation, by and large, or lack thereof--it's nice that someone might darken the door of a church, but that's not equivalent to coming to know Him.