If you do some basic research on fuel cells, you will quickly learn that they are not a "leap forward" by any means. In fact, fuel cells are a big step backwards because they cannot be plugged into the wall. They must be refueled with hydrogen, CNG, etc. and produce water or other byproducts as a result of the reaction.
No, fuel cells are a non-started for consumer electronics. They are just another way to maintain the status quo and to tie your electronic device to a hydrocarbon source. Even the hydrogen for fuel cells is not produced in a green way, but rather from fossil fuels. This is not part of the Apple ethos.
There a still, cloudy days, and days away from geo-thermal. 'water' and other byproducts (e.g. carbon dioxide), are pretty good alternatives to point source pollutants, and the need to be 'always' on will go from luxury to requirements as health and home fall into apple's portfolio of consumer services.
I'm looking at my power, UPS and local power requirements now (I'm in tornado and ice storm alley), and it's $40K for 20KVA (I have a 100 amp and 200 amp service 208V service for a 4 acre farm) Solar setup (and no local credits). I'm spending $2000 year on electric, so the CBA is telling me NOT to go there, but to invest in local CNG generation. Fuel Cells for that would be a lot nicer than the classic piston generator (noise and efficiency).
Scaling it down to the critical few... having a 4KVA (roughly 30A), would cover all my critical items (security/home automation, internet (I'm on fiber, and a GSM backup), an essential lighting and a microwave) I'm good to go. Using 3 or 4 10A Fuel Cells services would scale nicely for me.
Again, I don't see apple building these 'into' devices... but I think they will be the new 'bricks' of the future for charging/powering equipment... a power cord, a 'fuel container' slot, aa fuel cell combo with power transformer to step it down to feed laptops and network devices and charging phones, and the ability to power on the fuel cell when the electrical power is off or unstable.