Ok, I beat ya to it:
http://www.nejm.org/doi/full/10.1056/NEJMhpr1107519
Scroll down to Fig. 1. At current rate of residency growth (~.9%), even by 2020 there will still be more GME positions than total US MD+DO grads. Assuming no change in residency spots from today's #... still more positions available than total US grads. A reduction of 1% in positions (which I'm not sure is happening anytime soon) on the other hand would spell trouble about 2016-2017. All of this said, this article does not take the added AOA residencies into account (I'm not sure if they included the other matches, e.g. SF, either).
While things are going to get tight in the coming years for grads, I think it's safe to say that a DO grad, who passes his boards and doesn't have red flags, will have a spot waiting for him someplace. If he flushed opportunity down the toilet, then that's another story. FMGs and US students who went abroad are already seeing the crunch though. That's another story as well.
If anything I'd be more worried about landing a job as a pharmacist in the next few years. Looks like it's getting tight out there...