To me, the phones primary purpose in this scenario is to maintain state.
I can be working at home and instantly sleep my "phone-computer", slip it in my pocket and then resume right where I left off when I arrive at work by re-docking it.
Exactly! Even now I'm annoyed that I have to type on my iPhone keyboard when I'm sitting at my computer and someone sends me a text. Would infinitely prefer that when I'm in proximity of my computer and logged in that the phone functionality was available in the computer's OS and on screen.
And then being able to get up and carry what I was doing on my computer wherever I go would be the next step.
Wouldn't it be simple enough to write an app for your phone that would check if it was connected to your "home" wifi and then upload incoming sms messages to your desktop/laptop.
The phone app could wait for you to type a reply on your PC which is then sent back to the phone and then the phone would send it.
I'd be amazed if something like this does not exist.
I can be working at home and instantly sleep my "phone-computer", slip it in my pocket and then resume right where I left off when I arrive at work by re-docking it.