Kt is right about the Airfones in that they are rarely used. I believe only three or so per cabin can be used anyway, so is there really a point in one at each seat?
I do think there should be Airfones in the cabin for Medlink use etc. Perhaps, going back to my selected seats idea, only a few seats in Economy would have them, those being preferred seats anyway?
I was including them in the scenario with the PTVs on the narrowbodies because they are part of the Rockwell Collins system, and double as the remote control.