It's not "if", it's "when" this Paleo movement goes mainstream. My prediction is that starting next April, we'll see the first of an ever growing trickle of magazine articles, CNN stories, and various other references hit the mainstream.
A short list of my reasons this thing is (and will continue) blowing up:
1) It works.
Robb Wolf, bestselling author of The Paleo Solution, has a completely rad podcast that has over 100 episodes. Yet his book is a bestseller. People are buying the book because they are getting some initial results and want to tune in even better (or support him). Don't let this give you any ideas Robb, but I'll buy absolutely any book you guys write or even forward. The same goes for Mark Sisson.
2) It's not a religion.
It's science, and it's not bound to any a priori beliefs. As new data sets come in, the diet gets better. The role of saturated fats is something Cordain has come around on, for instance.
3) You feel better.
Atkins was onto a lot of things, but chowing down on a couple of those artificially-sweetened sugar-alcohol bars would give you one mondo case of the trots. Eating Paleo actually heals your gut, so cheating makes you feel worse, more hungry, and more lousy.
As people continue to try this out, for free, for themselves, they'll continue to buy books like The Paleo Solution and The Primal Blueprint for themselves and their friends.
This will fit a classic J curve and start to emerge around next April in a big, big way.