Type

I don't share the enthusiasm about iPad and tablets in general. Although it's a great device, it's usability is limited, partly because of incompatibility to the traditional PC world where I still spend most of my time. PC "compatibility" it's not such a big issue; not everybody is PC dependent and there are apps for almost everything. In fact I trouble only with input; although I don't type too well it's still the best approach to enter text. The iPad is a very good output device but not a good enough input device. Laptops are much better in input but weaker on mobility (inclusive battery life). The best I could imagine is an ultrabook i.e. Applr AIR, which has almost iPad like mobility but is a "real computer". 

So the fundamental issues is typing i.e. input. How can it be solved?

Make typing "cheap" 

Under "cheap" I understand that the keyboard consumes less from the most valuable mobile device resource; place. The keyboard should be as thin and energy efficient as possible while still supporting typing well. One example of this is the Microsoft surface but traditional keyboards also could be made lighter and thinner while keeping the good feel of typing. Maybe a dynamic surface could be developed, which is very flat or fold-able while out of use..  Projected keyboard with a typing glove to simulate pressure on the fingertips while typing... I don't know.

Improve tablet typing

The iPad already has great type support maybe it could be improved even further. A good typing software could guess what I plan to write and help me to do it faster.

Voice command

Siri paves the way. However I can't imagine sitting in my office and talking e-mail, documents, excel tables into my computer. 

Scribe

There was a time when many thought (including myself) that scribing will be an important if not the dominant input method. It didn't happen that way but who knows when it will come back again.

Conclusion

I think typing will be the dominant input method in the future. We are so used to it that it's hard to imagine reinventing it. However it my happen with new software and hardware invention which make typing easier, simpler while requiring much less place than now.