Computing power is not the limiting factor. Far more relevant are the display, which has efficiency physically limited by its luminosity -- and we're less than

Computing power is not the limiting factor. Far more relevant are the display, which has efficiency physically limited by its luminosity -- and we're less than a magnitude away from the limit. Even disregarding that for e-ink, there's the radio, which is limited by the channel capacity, from which I'd say we're also less than a magnitude away for isotropic radiation.