Well the Galaxy Note at 7" screen is possibly the max for something that can reasonably be used as a phone, but possibly not your computer. So I don't see smartphones doing that anytime soon.
Whilst for some years I have kept away from 'smart' phones as the protection wasn't really there. That has obviously changed somewhat with the introduction of the Avast! Mobile Security suite.
Whilst some tablets may have phone access built in and a 10" (ish) screen making them somewhat ungainly to be used as a phone whilst out and about. Without having something like a bluetooth headset, so you don't look like a dork talking to a tablet.