One reason for the popularity of these devices is that people are producing more content. Folks aren't watching CNN/BBC on an iPad but self produced Youtube videos and they're reading more than NY times bestsellers on a Kindle.

There is an assumption here that people with a PC will automatically become producers which I think is wrong. For people to become producers they need incentive and opportunity. These devices and the ease of content creation is means the opportunity bar is much lower (e.g. you don't need to get a publisher to agree on a manuscript to publish); and the incentive is higher (you can monetize content you produce whether its apps, books or videos much more easily).

But, if you spend much time on YouTube, it is surprising the range of people who have become content producers. To give just one example, my wife is fascinated by all the people doing makeup tutorials. These are people who might have explained things to a few friends, maybe, and now they have audiences of hundreds or thousands. Most of them are made with webcams on their laptops, and there is no reason they couldn't do the same thing on iPads or iPod Touches.

But post-PC devices are only partially replacing the PC - in those areas where they're better than PCs. We're not losing anything, only gaining something new.

How is it consumption when someone e.g., records a song in GarageBand?