How Much Phone Do You Use On Your Smartphone?

The new iPod Touch asks some interesting questions about the concept of a smartphone. At its heart it is an iPhone 6 squeezed into a 4" screen and body. To buy it outright costs an eye-watering $350 less than the equivalent iPhone 5S.
That's an awful lot to pay for a GSM/LTE radio and associated antennae.
Many years ago, when Bluetooth was in its infancy I talked about how the technology offered the opportunity to decouple the different elements of our technology, whilst keeping the experience intact. At the time I was comparing the capabilities of the Sony Ericsson P800 all-in-one (I hesitate to call it a smartphone) and the Palm Tungsten T/Sony Ericsson T39 combo.
The iPod Touch looks like it could form the basis of a modern day equivalent. Add in a small, light and cheap LTE phone and you have all the functionality of an iPhone at less than half the price.
Except you'll be missing one critical piece of the puzzle: voice. You'll still be able to make and receive voice calls, but unless Apple allows the iPod to serve as a Bluetooth headset you'll have to make them through your handset.
Apple could easily add this capability, but why would it when the iPhone represents two-thirds of its business? You could dump traditional voice calling completely, switch to Skype, for example, which gives you a real telephone number for your IP calling. You'd need to bump up your data plan, but then the initial purchase price savings, the savings on voice minutes and texts; plus the reduced replacement cost when its time to upgrade; would all ensure that you end up well ahead financially.
This isn't a thing that Apple could countenance. Which makes the decision to make the iPod Touch such an attractive device compared to the lower-end iPhones seem a bit strange.
Seems like a strong indication that Apple will be revamping those iPhone 5 based models sooner rather than later.