to be honest i don't think the AMCAS problems are going to affect the number of people applying at all. people who intend to go to med school are by nature very motivated and driven (of course, there are exceptions, but i'm talking about the majority). i highly doubt that someone is going to take four years-worth of killer science classes and then take the MCAT, not to mention the other stuff that goes into med school applications, and then suddenly decide to completely put their future on hold because they don't like the way the application works. sure, this year is especially bad with the new application, but the fact is, AMCAS has always been extremely inefficient--it's just the reality of applying to med school. every med student before us had to go through AMCAS. if you want to go to med school, you just deal with it--that's just the way it is.
if there *is* a population of people who do indeed decide not to apply this year due to the app, i'd say it's most likely the less-motivated applicants, not necessarily those with lower stats. there are plenty of people with high numbers who apply to med school simply *because* of their high numbers, because they see med school as a sure thing, a safe career, not because they're interested in becoming a doctor per se. i've seen it. you could argue that those with lower stats may be even MORE motivated than many of those with higher stats, because getting into med school is way more of an uphill climb for them yet they're persevering anyway.
just my thoughts.