Some Info
I've been wondering the same thing - here is what I know.
First, all 2013 Xb's produced after August will have a touchscreen audio interface - so if you get a 2013, consider whether you want an older one without touchscreen or the newer one with touchscreen.
Second, Scion models are generally supposed to be refreshed or replaced every 4 years (part of the Scion approach to appealing to the younger market). The Xb was redone in 2008 and is way overdue for a remodel or replacement. They were supposed to be axed for 2013, but the new boss at Scion likes the Xb, so it stayed around.
Third, the Xb is based off the Matrix platform, and the Matrix was supposed to be axed for 2013 as well. So not sure what is going on, but there are no guarrantees the Xb will be around for much longer.
Finally, Scion sales are down, as of August dealerships have been allowed to drop the scion brand with no penalty, so there may be fewer out there offering Scions...but Scion apparently showed a sketch of a sub-compact Crossover that will be built. This could be the replacement for the Xb and fit somewhere between a matrix and and Xb (just a wild guess)
It's anyones' guess whether they will keep the Xb (and Matrix) until the replacement comes out, or whether they axe it. They might think it good policy to have some sort of option out there until they get the replacement, but who knows.
So the 2014 Xb is kinda uncertain right now. They may have something up their sleeve that hasn't come out yet, but there's no info out there.
Good luck!