You nailed it Doug. I'd even add that AAMC is flying a little blind as well, given that they can't really take the experimental scores from the last two years seriously given that some people may have just guessed their way to an Amazon gift card. When the exam changed way back in 1991, it took three years for AAMC to zero in on what they wanted. The major complaint back then was that the real test was not much like the practice exams they released (AAMC 1 and 2). I'd venture to guess that it will be the same thing for the next three years, where the actual exam is not like the one sample exam they released, simply because of the girth of topics tested is way too large for it to be possible to cover with just a single exam.
TBR has taken the attitude that the books and exams will be revised twice per year for the next three years until they settle in on what they want. The new TBR CBTs (coming out in February) will cover what we believe will be emphasized, but we know we need to add an exam or two per year to the collection each of the first three years (there will be four to start).
The new section has some exciting topics, but it's anyone's guess what they'll emphasize. Will it be a bunch of psychology experiments and theories from entry level classes? Will it be hypothetical studies in sociology that deal with the 'isms' of the world? Will it be biology passages on the functioning of the eye or ear or nose? All three of those things fit in the AAMC list, so that section is intriguing. If you are lucky, your version will be more biology than anything else.
It doesn't look like the physics, general chemistry, or organic chemistry will change much other than a few topics being omitted here and there. Whether the passage is about a tidal volume of the lung or a piston expanding, it would seem that questions on PV=nRT will still be what gets you points. The amount of organic chemistry, physics, and general chemistry isn't changing; it's simply being relocated. For biology, I have to hand it to the guy in charge of the TBR book for weathering some of the comments of the last four years. He was building to this change and with the amount of biochemistry in the TBR book, it's spot on for the new exam.
The next year should be very interesting.