I wonder how many people would be keen to replace their home phone with a videophone if one is available for the price of a modem (~AUD$100?). Perhaps the reason why it is so uncommon is that there is no demand for it. Yet I would be the first to look seriously into it if it were available. All the technology that is required to produce a simple videophone for the mass market it is already here, so why isn't anyone making it?
This is how I think it could work. Of course, it needs to be connected to the internet. As with Skype, one can choose to either make a voice call or a video call. Suppose this is simplified so that one begins by making a voice call. Then upon request, he can press a button and his video image will appear at the other end, and vice versa.
Yes, I am really hoping that the next evolution of the home telephone will be a simple videophone. I emphasize on "simple" because that is the only way to make it appealing to even the most technophobic individual; the proverbial grandma or grandpa. As with voice recorders, perhaps one might even be able to record a video clip of the conversation, for playback if grandma misses seeing her grandchildren.