Good point, there is an acceptance that as long as a device is rechargeable it is 'green', although it may have a net power consumption that would be unacceptable if powered from a primary battery. Transferring these devices' smart power-saving tricks to battery-powered devices might be something we will see, but we need a new, greener primary cell first.
Some fuel cells look interesting there, some claiming to be recyclable.
Professionally, I am concerned about the EMI background noise floor rising at a measurable rate, as you point out.
Blog Make a Frequency Plan Tom Burke 17 comments When designing a printed circuit board, you should develop a frequency plan, something that can be easily overlooked. A frequency plan should be one of your first steps ...