From what I know Bitcoin mining requires a lot when it comes to the computer that does it, so if we are talking of this much power on a mobile device or a smartphone, I can say that that is too much, but then again we know our technology now are making things possible so I think if there would be a demand for that, it will happen.
I don't think it can be happen since smart phones has minimum item in it. Low Ram with lowest processor can burn the phone. We all are aware that bitcoin mining use 100% usage of process and it can eat the ram speed.