In the mountains in between there are tons of nooks and crannies where there will simply never be wireless coverage. And, yet, people live in those nooks and crannies (one of my IT coworkers, for example). What if you're stuck in one of those canyons, with one of the many luddite mountain folk, and you need to use your device? (like the example I gave, where you need to use a landline to make a call, and you have no connectivity options at all for your handset) With _YOUR_ convergence device, you're screwed. No addressbook, no local notes store, etc. With _MY_ convergence device, I'm fine. I can ask to use their landline real quick (just because they're luddites doesn't mean they're jerks), and everything is great.
After all, X-terminals, Javastations, Thin-Clients, and their like have yet to displace low-end computers. The balance between these two perspectives is a constant ebb and flow, I'll give you that. But neither ever eliminates the other.
So, you're talking about idealistic pie in the sky theoretical convergence, and I'm talking about here-and-now practical convergence. (which isn't actually a criticism on my part, I often talk about that kind of "theoretical/idealistic/as-it-should-be" type of technology as well, but as Mahan pointed out wrt naval warfare, if you don't keep yourself fully immersed in both the theoretical and the practical, you're going to have problems .... practical beats theoretical, but the balance beats the pants off of both of them)