Maybe it won't be handheld, even, but embedded :)

I think we're likely to have wearable computing before embedded ones. I won't complain about being wrong though!

The iPod touch is wearable computing, at least as defined by futurists predicting such things 15 years ago.

There will be something else, not handheld devices. Think about it, iPhone 4 is not that different from the original iPhone. Better specs, more features, more app, but not totally different.

Still an exciting world to live in though =).