Actually, the iPad has sold overwhelmingly well among Boomers. They are, in fact, the main reason that iPad sales have been so strong. In fact, on another iPad forum site I frequent the single largest age group of iPad owners is over 55 years of age and the median age of those on the site is 45. And no, it's not iPadsForGeezers.
As for personal devices becoming "extensions of ourselves," I'd recommend another Boomer favorite, "The President's Analyst" starring James Coburn from 1967.
A Post-PC world? I'm skeptical. One interpretation of that comment is Apple bravado taking a shot at "PC's." And that's been a wet dream at Apple for nearly 40 years. Yet Apple still constitutes about 10% of the personal computing world.
Another interpretation is Mr. Jobs hyping devices used mainly for social and entertainment activities. But unless someone actually does some work now and then the disposable income to finance socializing and entertainment won't be there. Tablets have cut into PC sales, but new PC's still outsell tablets five to one. And while businesses have found a place for tablets, they're additions to, not substitutes for PC workstations.
Nor do I see iOS turning into a full-fledged computing platform crammed into a device the size and shape of an iPad. I'm currently sitting in front of four 20"+ monitors along with my iPad. I need all of those monitors to do my work and the computing power of two quad-core systems to drive them. Unless technology manages to overcome some rather stern constraints of physics, iOS will remain for the foreseeable future an operating system with limited functionality driving devices where portability and battery life trump functionality.