The age group for highest likelihood of Bitcoin adoption is off by 7-10 years I would suggest 13-33 or even 10-30 with a peak around 20. A teenager is way more likely to adopt Bitcoin than someone in their late 30's. In fact teens and tweens are a huge market for Bitcoin because they cannot get a Credit Card and are huge consumers of online content and services.
On a related note I would expect those in their late 50's, 60's and early 70's (Baby Boomers) to be a lot more receptive to Bitcoin than those in their 40's or even late 30's. Let us not forget that someone who turned 20 in 1969 (summer of love, Woodstock) will turn 64 in 2013. The baby boomer generation shook the establishment to its very core in their day, their children one the other hand are notoriously conservative and status quo by contrast. Let us not forget that teenagers always rebel against their parents, not their grandparents. The grandparents more often than not see the teenage rebellion as payback to the parents.
See: Zhoutong (17 when he started Bitcoinica) and Phinnaeus Gage (55 when he joined the forums).
