Arguably, these goals in terms of battery life / efficiency are already heavily incentivized for mobile developers - and by extension the iPad despite having "h

Arguably, these goals in terms of battery life / efficiency are already heavily incentivized for mobile developers - and by extension the iPad despite having "high end" processors. For mobile devices, generally, the strategy is hurry back to sleep, IE ramp up the CPU to do a job quickly then put the processor back in the lowest power state, and for many applications this works great. For the remaining applications, say mobile games, we might be limited more by the users desires (the best graphics, the lowest latency, the best colors, the most immersive sound) rather than this sort of hardware not being available. All this to say, I agree with you that such a device could still exist, I'm just saying we might be that far from it.