Ok, I'm going a bit far with the idea, but it could happen.
Data mining is where it's at. People tell Facebook all the things that make up their lives in order to 'socialize'. Now you're giving up your voice. This rambling non-sense that is the voices in your head. The stuff we can't get a computer to do or figure out.
For me: I'm excited to see the cell carriers loose sleep at night. It is known by techies that cell 'minutes' are actually data packets. Making it easy to do VoIP is what I have tried to do for a long time. No easy solution exists. Alas, now that all the carriers have moved away from unlimited data plans, they will welcome this since they can profit from the ~$45 per GB data plans.
I'll end the complaining here.
Now just imagine all the 'friends' you have on Facebook that you really do not want to talk to ...
Where this is all going? In less than two years it will be common for any social platform app to have a call button that allows a phone call to be placed over the data connection. Five (?) years down the road, we will have people who do not identify with a phone number; you will simply find them in social medial circles and hit call. You will get voice mail, etc. Sounds crazy? Remember those people who first ditched the land line? I had many people stop dead in thought trying to understand what I just told them. No home phone? What do you mean?