MY PERSONAL PREDICTIONS-
I think that due to its higher up front cost (remember the iPhone costs at least $2,000 with the 2 year contract, although you do get phone service) than the iPhone (I doubt that they'd drop the price for the 8GB to $199, it would make little profit while killing much of the profit from the Nano), they will have to add to the iPod Touch.
---Bluetooth--- This really should be a must, considering the potential market for peripherals that has not existed for previous iPods. It is a little supprising, however, that we have not seen any new peripherals since the launch of the App store, such as a keyboard, etc.
Even without new items, however, wireless headphones could become rather popular with the new iPod, and bluetooth would be cheap to add.
---GPS--- This seems really up in the air. On the one hand, it would add quite a bit of funtionality to the iPod (it would be an Amazing GPS device). On the other, GPS built in is really a phone use, and would be somewhat out of place. The large focus on locality Apps in the App Store hints that it might be useful, while the added cost would bite into Apple's bottom line. Unless Apple expects to gain the revenue back by selling (mostly having someone else sell and receiving 30%) location Apps to iPod touch owners, I would imagine this waits until the iPod Touch line diverges into a premium model an a more nano-esque one.
---Speaker/Mike--- I think that a speaker is unlikely, since the quality and volume of music would have low potential. This has never really been a consideration for Apple in the past, and would take up significant space (which they are obsessed for, with good reason).
For a microphone, I also doubt it. It would really seem to encroch too much on the iPhone, and while it couldn't really be a replacement (you need your phone all the time, not just when you have a Wi-Fi hotspot), it would make it seem like a phone. Product differentiation is important.
Plus, for either of these, A small add-on to the dock (they already have many commercial versions of portable iPod speakers) would add functionality when you need it (while Bluetooth would be something you would want all the time).
---Camera--- I really have no idea. On the one hand, phone cameras still generally suck and were added mostly to have more features. The iPhone had to have one to compete, but Apple hasn't put too much effort into it. On the other hand, 2 megapixels is decent and the lens isn't too bad, so the iPod touch would find one useful. But without a cell network to upload photos on, people would be better using a real camera and dowloading later. When decent (i.e. 4x6 printable) shots can be put inexpensively into a phone, which is dependent on getting a quality lens to a small size, not pixels (I had a 2MP camera, it was far superior to the iPhone because it had a real lens), then the iPhone could take on consumer level cameras.
---Volume Control--- Not a bad idea, but Apple does like the double click control (which I find quite useful, but not a replacement).
---CAPACITY--- I don't think we will see a 64GB model in September. The chips just aren't affordable yet. The 32GB was a surprise, and it will likely be closer to the same time (February) next year when we see an upgrade. The problem is that Flash prices per capacity are dropping more than half per year, but not enough for twice a year. However, given a lack of a capacity upgrade, they will have to make some other substantial change (well, I guess they didn't last year with the shuffle, but its more of an afterthought).
---Chrome Back--- Maybe they'll drop it to bring it in line with the iPhone, but most likely it will be whatever the other iPods are. A backing like the front of the iPod classic would be nice.
And speaking of the IPOD CLASSIC, its days are numbered. Perhaps we will see a hybrid version in the mean time, and it will always be cheaper to use a hard drive, but in a year and a half when 128 GB flash memory become affordable, that will be enough to end it. 500GB would be great, but not enough for the added size and slow speed that would hamper OSX. The iPod touch will be the top, and while we probably will still see the nano (taking the place of the shuffle in some ways), they could be an intermediate.
