It's typically pretty easy to get a robust conversation going about whether VoIP is dead or not, and what each of us means when taking a position either way. Interesting viewpoints exist on either "side" of the debate, relevant for technology enthusiasts and developers but rarely of interest to the mass market that will use the technology.
One might as well say, in advance, that now that Twitter seems to be reaching some sort of inflection point or critical mass, lead technology adopters and developers will move onto the next big thing. Technology rarely is interesting to technologists when it is simply "there."
I remember the same thoughts expressed about session initiation protocol. The disenchantment isn't worrisome. Technology enthusiasts simply have different values than mainstream users, who just want value they understand, easy to use, acquire and support, at fair prices.
Technologists love technology. Most people don't care, so most large, successful businesses are built in ways that hide technology from end users. It makes about as much sense to argue about whether "electricity is dead, or not," as it does to worry about whether VoIP is, or is not.
Technology always is most successful, and most ubiquitous, when it is just furniture. VoIP isn't yet "just furniture." But that is where we inevitably will go.