Although I disagree with parts of the article (ok, a big part of it), I have to say it's an interesting article: an array of ideas on how to create a mobile VOIP infrastructure based on wireless networking technologies.
I really think VOIP and SIP will become more and more part of our day-to-day communication systems, but mobile carriers will evolve to incorporate it. My opinion is that there's no free when the resources to implement cost.
In his article "The Death of the Mobile Phone Carrier", Mark McCarron goes deep to explain how to accomplish this, but in the end some money has to be paid - either to the service provider or to the infrastructure provider.
And that's where the mobile carriers do well - they integrate the infrastructure, services, support, management and billing (of course).
Go have a read on this article and comment in our forums too!