Some locations where that wouldn't work.
Thinking it through might have shortened your list some.
[*]One handed, on on a tube train, in rush hour, standing up, dangling from a strap.
Same for a tablet with a Touch UI. One hand to hold it, one hand to do input. So one handed is out the window with anything bigger than a smartphone. An iPhone fills this need much better than a Tablet.
[*]Lunchtime on a city park bench(sunlight, bulk, and where do you put it on the walk back to the office?).
Except a tablet with a LCD display will be as bad in sunlight, e-ink displays don't let you do 95% of what your tablet does (web, games, videos...) and a tablet is as bulky, so where do you put it on the walk back ? In the same bag you would have carried your laptop in.
[*]Any public place where the size of a laptop might draw unwanted attention (personal security issue).
You mean an expensive Apple Tablet would not draw unwanted attention ? This one is your worse one yet. If a guy is ready to jump you for a Macbook, he's not going to have any qualms about taking that tablet for a ride either.
[*]In any crowded public place where the bulk of a laptop and fragility of it's hinge makes it a larger target for damage (device security issue).
A tablet won't be much more solid than a unibody aluminium macbook and not much less bulky. If someone manages to knock your macbook over, he probably also would've shattered your tablet's screen.
[*]On a coach-class seat in a plane. Either I'm growing, or seat pitch is shrinking. Prob the latter
Yet people use laptops on airlines in coach class all the time. Non-argument. A tablet would also not give you as much liberty in what you want to do on the flight (limiting you to content consumption vs content creation).
[*]Any crowded place where you want more privacy than a laptop affords. Plane is a good example. Or stading in line at the post office (and you'll need long-lasting batteries for that!)
How would a 10" tablet offer more privacy ? Especially if you hold it up at the same angle as a laptop to read it. Are you suggesting setting it down flat ? Then what stops someone from peeking ?
This one is pretty bad too. Standing in line at the post office, be it a laptop or a tablet, if you want privacy, just keep it in your bag.
In short, it'll be convenience that does it.
Except a tablet is not really more convenient than a laptop, and not as convenient for many other uses.
And how about the ability to easily search - with a few keystrokes - that once-huge pile of books and magazines that now reside on your portable digital device? Have you ever spent time digging through a stack of old magazines to find that one article you really need right now? I have. It stinks.
How about the ability to easily copy and paste information (say, to your Evernote notebook) to assemble it in ways that best suits your needs?
How about the ability to annotate (highlight, circle, cross out, whatever) those digital books/magazines with a layer that can easily be hidden or revealed? Try that with paper.
The list could go on and on.
All this magazine, e-book, publishing talk is getting ridiculous. A tablet does not enable the iTunes Book Store. You can read books on a laptop, an iMac, an iPhone or an iPod Touch. You can read comics on those too. You can even read full books. A tablet doesn't suddenly make all of this possible.
So seriously, all the iTunes e-book are just a seperate rumor. I really doubt Apple would require you to buy a 799$ tablet to use the content they sell. They would happily sell it for all your other Apple devices or non-Apple iTunes capable devices (like a Windows PC).
If there is ever a iTunes Book Store, it won't be related to the tablet. If there is a tablet that is iTunes enabled, it's going to be sold as a media consumption device, not the "new e-reader for iTunes books!".