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.
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.
And then being able to get up and carry what I was doing on my computer wherever I go would be the next step.
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.
And enjoy some media / regular mobile experience in the interim.