Any of these device that does not have tactile text entry will fail. I'm talking to you too apple. MS's concept looks cool, but it will only fill a niche market.
The iPhone is different in this regards as tactile text entry on phones is cumbersome in itself and a virtual keyboard is fine for something tiny that fits in your pocket and they're already regarded as companion devices, not full fledged computers. Still there are many people I know who will not purchase one because of the lack of a tactile keyboard.
If these tablets have no method of tactile entry they will be relegated as companion devices and when it comes down to the choice between a netbook/notebook and a tablet device, most will choose the netbook/notebook because they are used to entry on a keyboard and will view them as "full computers" and the tablet as something I will also need a full computer for.
Now if they're smart, and I know you are apple, they will release something that is both a tablet and a netbook.
I can picture the commercial in my head now. The disembodied hands playing with the device and all and apple's narrator describing what it can do.
- Say you need a notebook to jot down notes during a meeting, draw some diagrams, share with your co-workers. It can do that.
(shows disembodied hands writing and drawing on the tablet with a stylus)
- Say you need a book reader to review those notes, surf the web or read the works of your favourite author. It can do that.
(shows disembodied hands flipping pages, scrolling etc with their fingers)
- Say you need a media player to watch movies on the go, listen to your favourite music or play a few games. It can do that.
(device flips to landscape and shows disembodied hands manipulating video/music/games)
- Or Say you just want to use it as a plain old laptop. It can do that too.
(shows device magnetically clicking into a keyboard base)
- Introducing the brand new 10 inch iBook Touch only from apple.
(Screen closes down on base keyboard just like a normal laptop)
So much trouble and except for size, you're pretty much describing any other tablet notebook out there.
For instance, take a look at the Thinkpad X61 tablet or the X200 Tablet. 12 awesome inches. (4:3 and 16:10 respectively).