While I am an avid user and proponent of video conferencing (to me this means all forms of visual communications), I don't believe it is going to replace voice calling - at least not all voice calls. As with other communications technologies, it will replace only part of the other means of communications.
You see - sometimes video is just not what we are looking for. Or at least it's not what is necessary to succeed.
This month a group of mobile operators and vendors unveiled an initiative called "One Voice". This initiative is about adopting IMS over LTE by focusing on doing only voice and SMS - what all mobile handsets are capable of doing these days.
I have written about it already on my VoIP Survivor blog and over at NoJitter, but there is one thing I have neglected: IMS started as a big promise - a promise of providing rich multimedia, along with rapid service creation and deployment by operators. It got bloated to the point where it was impossible to implement and deploy over networks, which made a lot of VoIP technologists skeptical about it. I know, as I have been one of them for a long time now. But I think it is changing.
IMS is taking a different approach now, at least from the looks of this initiative, by first focusing on the "simple" stuff of doing regular voice calls and adding text messaging to it; instead of promising the world. From there, it can grow in a more controlled fashion to live up to the dreams that were made around it.
In the words of a good colleague of mine: "they are now investing in 90% of the revenue they are generating, which requires only 10% of the effort".
For me it's a wakeup call, that sometimes all we actually need is "just" voice.