Here's what I think...
As far as case design goes, the only thing I might expect to be upgraded is an offering of a black aluminum case due to the success of the blackbook. As far as HD drive options, maybe, but only as BTO.
For processors:
I'd expect the low end MBP to get the 2.3 Ghz or the 2.5 Ghz. The problem with giving it the 2.5 is that the high end MBP will only be 0.1 Ghz faster at 2.6 Ghz (the 2.8 is too expensive to offer stock, if offered, it will be BTO like the current 2.6). So, I hope we get the 2.5 on the lower, but we may get the 2.3, which is still faster than the current offering. If we do get 2.5, as I said, Apple will have to strive to differentiate the offerings a little more. This may mean a beefier hard drive by comparison or 512 vs. 256 of vram.
For graphics:
It's likely it will stay the 8600m GT, but maybe with 256mb and 512mb variants (gosh I hope). The forthcoming 8800m is said to be TDP of 35W, which is just too much for a 15.4" notebook. Unless Nvidia releases a variant that fits in the 25W TDP category, or one of ATI's upcoming 55nm mobile parts fits in that category, you'll see the 8600m hold strong.
Hard drives:
Maybe a modest bump (160 and 200), but I don't expect 7200 as standard. That assumes a need for that kind of performance on every owner's part, plus it adds extra base cost to the MBP. Perhaps we will see the 320GB capacity show up in the 5400rpm version as well.
Edit: And maybe if we're lucky they will let us change our own hard drives without voiding the warranty with an internals redesign.
Memory:
They will stick with the DDR2-667. The FSB of the penryn is 800Mhz, but I think the memory will still stay at its current point. There's no way you're going to see DDR3 any time soon. Just as when DDR2 first came out, it's worthless. For DDR3 to be of any value, FSB's need to reach speeds that DDR2 can't achieve and then DDR3 will make sense. If you go onto Tom's Hardware you can see that they overclocked the FSB up to 1600 Mhz on a new quad-core Penryn test system and it had no benefits over the stock FSB. This is because Intel has moved to techniques that try to be as memory frugal as possible (the 6 MB of cache will help that).
For any other goodies (like WiMax), just look at what the upcoming Intel Platforms support.
I can't wait for the January update to hit, but I just wish it was Nehalem and not Penryn coming (those integrated memory controllers are going to be a huge step for Intel).