Before videotelephony can take off you need there to be niggling little things like:
(1) Enough certainty that you can video-call the person you want to talk to
* Interconnect between mobile carriers, and with fixed telcos offering video and with internet services
* Near ubiquity of phones with video capability & access to broadband (cellular, wireless or fixed)
* Either a presence-enabled address book or a called-party handset/client discovery process that lets your handset know that you can make a video call to them
(2) A more flexible way of making use of video when you want to – so it becomes useful, rather than as a way of showing how spooky you look when filmed from a blair-witch-style perspective though a wide angle lens.
* The ability to upgrade and degrade between video and voice in call.
(3) A recognition that for all except the most exceptional circumstance (A new grandma wants to see her first grandchild, talking to your family on the other side of the globe scenarios) customers expect the price of video calling to be near to that of voice – because they have got used to ever cheaper voice calls, and most of the time do not see the added value in a grainy, moving picture.

So my recommendation would be slip video capability into handsets and clients quietly over the next few years, continue with rolling out all kinds of broadband, build up interconnect & start working on the service usability.

Give it another 3-4 years before plugging adverts to any but niche or early adopter segments.