What about some of the advances in micro-generators and Fuel-Cells that I have read about?
For instance, I have seen one of those tiny turbine engines running to power an equally tiny generator, and it looked to provide a hellofa lotta power for its size. I know the military is putting them into some applications in the field, so it will probably not be too terribly long before we see them on things like Laptops/tablets or cell phones.
I haven't seen anything recent on these. Any keywords to google? The key thing for a consumer electronics application is ease of getting the fuel. People don't want to have to head out to the shops to get it every few days, which is why rechargeable batteries are the current winner.
I would like to propose this as a thread for people to write in their predictions for the next year and the next decade, when practical with probabilities attached. I'll probably make some in the comments.