I am interested in seeing how they collected their data. If "25% said they would be using Google+ more often" then that implies that more than 25% of the 2000 teens surveyed have used Google+. That seems a bit to high for me considering out of the 1800 people in my high school only two people(twins, other then myself, have even used Google+. The majority in my school (Yes, gross over generalization)that uses Facebook don't even like it. The only reason they use it is because they wan't to socialize with their friends, but know of no other way to communicate through a network (Sorry MySpace). In other words, the only reason people use Facebook is because everyone uses Facebook. I hope you can see the fallacy in that.
I do see Google+ slowly taking away from Facebook's hold on teenagers, but I cannot see a complete transition from Facebook to Google+ happening. Perhaps a small group of teens that go into the world of Google+ with an exponential growth, similar with MySpace and Facebook. I see the beginning process being similar, but not a complete end of teenagers on Facebook, but rather just a slightly lower activity level as people use both Google+ and Facebook, or solely use the former.
P.S. How did 14-17 year olds even get a hold of a Google+ account when you have to be 18 or older =P
P.S.S. How was this comment. This is my first comment on Hacker News. Hope this was a quality post.