Here's what I think:
Organized religion is way behind the times, developmentally speaking. Most rest their concepts in mythic structures that simply do not resonate with most modern to post-modern societies. For a while (early 1900's) extreme rationalism came into vogue, and if you were going to have a "heyday" for philosophies like atheism/agnosticism, it would have been then.
But then WWII happened, and in times of extreme crisis, people naturally drift back to "knowns", and organized religion was one of those "knowns". But, its tough to stuff the genie back into the bottle, and the 60's experimentation with many things, including attitudes regarding religion, began to be either rejected or expanded in a completely different context. It was after this time period, and our encounters in Asia, that Eastern influences began to infiltrate the mainstream.
The problem was that these philosophies expanded upon an idea that wasn't explored much by Western theologies (which focused on the "Great Thou"). So this new focus on the "Great I" was very exciting, but took a really perverted form in the "me" decade of the 80's. This would also be the time that Evangelicals, sensing their weakening grip on the theological front, formed their new message and attraction to people who felt lost in this sea of uncertainty.
It was only with the invention of the internet and access to knowledge stores that were previously hard to find, that people started to feel comfortable moving away from mythic structures because they finally had transpersonal opportunities available to them that didn't require the "go-between" of the Church. So that, now, when people say "no religion", it doesn't necessarily mean"no spirituality", it simply means they don't feel connected to or the need for a community to explore their sense of spirituality. Spirit has become too big of a concept to be contained by one religion. Its no longer taboo to explore outside the dogma of your background religion to see "what works for you".
So, what is really happening, is that the worldspace with regards to religious/spiritual opinion, is finally evolving beyond the mythic stagnation it was in for quite some time. Its shooting right past rationalism and into pluralism and integralism. It no longer matters if your devotional is from one tradition, your meditation from another, and your expansion/identification from yet another. Just because one practices a Buddhist meditation technique doesn't mean the person considers themselves "Buddhist". So, the person says "no religion", even though their practice has its roots in a traditional religion, or two, or three.
This only holds true in modern to post-modern societies. If you go to a developing society, then traditional religion will probably hold steady or be increasing, because the structure is compatible with the worldspace they understand. You can't be successful, on a large scale, by asking people to jump a developmental sequence or two. Its like climbing a ladder with a couple of rungs missing, it seems risky and foolish to climb. So, in that sense, organized religion will always have a place.
You'll see it's all a show, keep 'em laughing as you go, just remember, the last laugh is on you, and always look on the bright side of life!