They may add bluetooth, add GPS, move the memory up a notch for the price, improve the battery, add an FM radio, add a second earphone jack, add a TV-out, add a mic, or do all these things.
Bluetooth? Every other Mac has it. So do competing players from Philips, Samsung, Insignia, Sony, and more.
GPS? Would be approriate considering the location apps coming out. Even if all it would do is turn on to find location then shut off.
Memory? This is the one thing we know that keeps going down in price. With Apps to sell, more memory would be desirable.
Battery? Unlikely without increasing the Touch's size. Bad thing to do as it would obsolete every Touch accessory out there.
FM? Again, competing players have it. In fact almost everyone else has it, and many have FM recording too.
Second Jack? Not likely. Nice touch on the Inisignia Pilot though.
TV out? In my dreams.
Mic? Would allow VOIP applications. Apple probably won't, as then the Touch can be a phone, and Apple would rather sell you an iPhone.