I agree. While I am an advocate of Apple design, I think that consumers have no widespread experience or acceptance of this class of device. I don't think an Apple tablet would be popular or very profitable for several years--I suspect that it would be akin to the Apple TV or the Newton, which was ahead of its time.
There's now quite a bit of consumer experience with and exposure to e-readers such as the Kindle, the Sony products, the recently announced Nook and several others. The Kindle also provides some access to newspapers and other publications than books. Yes, these devices have relatively small, although growing, market penetration at this point. But the major problem with all the e-readers isn't that they're unknown, it's that they're simply not very good. Monochrome displays, unattractive designs, clunky hardware, dubious user interfaces, incompatible content/hardware ecosystems, all of those things make today's e-readers intriguing in concept but limit their target market in real life. And at $250 and up, the buyer needs to be pretty motivated to buy one.
The proper comparison isn't to the Newton or other early PDA devices, where the concept was indeed well ahead of the hardware capabilities of the time. No - instead think about personal MP3 players. Apple didn't by any means invent the MP3 player with its iPod. What they did was bring out the first MP3 player that was irresistible.
This came from a confluence of several factors: the newly available 1.8" hard drives for ample capacity (yes, 5GB seems tiny today, but it wasn't in 2001), Apple's legendary design skills that resulted in a highly attractive product, the clean and innovative user interface, and last and by no means least, the convenient iTunes Music Store and its DRM protected content that addressed both user needs and music company fears. Could somebody else have done all that? Maybe, just possibly — but they didn't.
I argue that the projected Apple tablet device is at a comparable point in history. Electronic access to news, books and magazines is on the rise, while the traditional paper versions find themselves in crisis. Specialized electronic devices (i.e. other than computers) to access published material have existed for some time, but they're simply not compelling. Narrow focus electronic book readers are too limited in scope to to justify their cost to all but the most motivated audience.
All this says to me that the door is open for someone like Apple to replicate what they did with the iPod in 2001 (and more recently with the iPhone). In today's terms that will mean much the same as back then: superior hardware, software, interface and appearance, backed by a robust ecosystem to deliver content, and all integrated in clever ways. Apple has, probably better than any other company, the ability to deliver on those things. By comparison Amazon has done a decent job with the back-end, but is weak at everything else.
The projected Apple tablet seems likely to cost at least three times as much as today's e-readers, i.e. perhaps $800 vs. $250. Obviously to justify that it both has to do more and do it better. For those to whom this seems like a stretch, let me remind you that the original 5GB iPod, introduced on 23rd October 2001, was priced at $399. That's about $480 in 2009 dollars. People said Apple was nuts.
It's going to be interesting...