I have to say I am with Commodorejohn and Linde on this subject, there are to much gain in stationary/laptop x86 PC's that can't be traded away for handheld touch devices, sure some people can do most of their computing needs on handheld devices but every single one I know have either a stationary computer or a laptop, they use their handhelds at the TV under comercials and on the go.
I know people in a wide age span, my youngest sister is 24 years younger then me and all of em use full size x86 Machines.
Ive even noticed a wide range of heavy handheld device users use it mostly for their Facebook/twitter/flikr needs and cheking the weather (beside Calling/texting) and as soon they need to type something bigger or browse the internet more then news sites they go to a x86 machine.
I don't know facts and numbers, I just state what I see around me and my eyes do not see the end of PC's.
I don't see how a 4-10" handheld could dominate the average joe's all computing needs either if he is a techie or not.
There is just so much you can not do without a mouse/keyboard and propper display size not to forget the ergonomics.
Just my two cents without going to deep in the subject.
Sorry about misspellings and such, im tired after a night with Stargate
Edit: Good night