HOWEVER, I don't know about all of the other features people have been pushing around (e.g., A4 chip, Retina Display, high-res back camera, iPhone4-esque design). Implementing too many of these features would most definitely cause iphone cannibalization (the iPad form factor differentiates itself enough); however, I could see a couple of these being implemented:
I'd like to think there won't be a rear camera. Although it would be really awesome (the iPhone 4 camera is absolutely stunning), it's highly unlikely. That would be a bit too much luxury for the iPod line.
I fundamentally disagree that Apple is terribly concerned about cannibalization within the iOS devices. A user is a user is a user and I anticipate them to be incredibly aggressive with the features this year for the iPod touch.
From my perspective the whole game versus Android is keeping developers paid and happy and by having traditional subsidized phones, iPads and iPods all using the same platform, this goes along way towards staying in it.