[ZiggerZagger]

Agree with a lot of what's been said. In the big picture, it's clear that we've already enjoyed the major bump in interest and maturation of the hobby associated with TPG. I believe Coin collecting enjoyed much the same in the earlier 2000's.

It's also pretty clear that we're now on the back end of the accelerated interest in higher-end Post-War cards. Prices have been dropping to a level just a bit higher than before the run-up. There was clearly some undervaluation in that market, but what happened was unsustainable. POP's are not truly limited for most Post-War 8's and above when compared with Pre-War, and whenever middle class investors become well and truly priced out of a market it just can't be a good thing.
The collectors who are in it "for life" (like most of us) have the advantage here. We're happy to sit on the sidelines waiting for any fever to die down, and for speculators to pull up stakes and cash out of the hobby -- We'll buy at a lower prices when they do.

I've been wondering if this small boom was the perfect storm of a very good Economy along with the Boomers reaching the peak of their financial powers? Sprinkle in some Speculators, some feelings of Nostalgia, and you get some mad prices.

So my best guess given all this is Short Term continued weakening of prices on the Post-War cards involved in the run-up (RC's of Rose, Clemente, Koufax, etc.). That should also include the 5's, 6's and 7's that got inflated in the run-up as well.
Medium to Long term, continued gradual appreciation across a wide range of key Post-War cards with intrinsic appeal to collectors. Pre-War to do it's thing, puttering along with solid performance -- maybe some room for faster appreciation with certain players.
Maybe '70's Baseball and Hockey/FB/BB to get some love, too.

I would be amazed to see another run on prices in the next 5-10 years like we saw in the past 2 years.