What you describe is more of a computer. I want that too, have done since those pocket organisers in the 90s, or the Casio Databank that played dial-tones of friends' numbers down the phone line.
What we really want, I think, is the ultimate portable computer. With a phone feature. I'd actually rather it was VOIP and everyone used that over 3/4G networks for most calls, but imagine that happening in the next 5 years - fat chance. This ultra-portable device would have the perfect form-factor of usable screen and keyboard, all somehow tucked into a pocketable device. Much like those old Psion devices, or the N900, only packed with decent hardware.
This is sort of what canonical is trying to do with Ubuntu and Unity. The phones they'll be coming out with later this year are said to be a "full os" in the form factor of a phone. The interface is made to allow you to pair your device with an external device (say screen and keyboard) and the interface adjusts its self to that form factor (think "responsive design"). So at say a public library, they could have these cheap terminals that people with phones can just walk up to and use with their phone as the computing platform and the peripherals as just an input interface. Right now every major manufacturer is putting out two OSs (chrome/android, windows/winphone, osx/iOS), and I think they're just now realizing it doesn't make sense, I mean google even touts chrome as mobile OS, why the heck are they making two? I don't think they have any plans to combine the two projects, but I really hope we aren't using java vms everywhere in the future. It seems microsoft is now rethinking windows 8 and their phones aren't selling well (for a number of reasons) and I think most likely they'll be coming out with a convergent OS soon. It'll probably be a rip off of unity or gnome shell.
The 4G standard actually specifies using VOIP for all calls - current 4G networks use what's known as Circuit Switch FallBack (CSFB), but the plan longer term is to move to VoLTE (Voice over LTE). See http://en.wikipedia.org/wiki/LTE#Voice_calls for more info.
What we really want, I think, is the ultimate portable computer. With a phone feature. I'd actually rather it was VOIP and everyone used that over 3/4G networks for most calls, but imagine that happening in the next 5 years - fat chance. This ultra-portable device would have the perfect form-factor of usable screen and keyboard, all somehow tucked into a pocketable device. Much like those old Psion devices, or the N900, only packed with decent hardware.