mm, with a shutdown, toggle switch, startup. ive seen laptops that can do it. also all that heat is bad for battery too.
I am sure engineers can figure it out.
I believe people interested in keeping money safe (which will be a small part of the users) will be happy to pay to mine as long as bitcoin survives.
Not the best example but Pi Coin was started on the idea of PoW and mining on phones. The concept is there. And consider scale, a mobile might only produce a small hash rate but enough cell phones/tablets etc and the hash rate of the network still maintains.
ASIC/cooling in a charging base, processing and connectivity in the phone. Charge and mine while you sleep. I'd buy it.
Ugh I think it was sexcoin that we used to mine on da phones back in the day