* the gopro hero 2 has built-in heat-up function to avoid quick battery run-down at low temperatures; they could add something similar to an EVF if this is really an issue
Good point. Unlike the rear LCD the EVF is physically small and recessed and I think behind another layer of glass with an air gap (not sure about that) so has some thermal separation from the environment therefore it wouldn't take much power to keep it at least at its minimum operating temp. There are other pros and cons to EVFs though.
* contrast-detect AF is also getting better, give it five years to be just as good as phase-detect AF for everybody except sports shooters
If by "everybody except sports shooters" you mean anyone who doesn't need fast, predictive auto focus, and subject tracking then contrast detection AF is already as good as phase-detect AF and has some advantages. But not sure I would agree that the segment of photographers benefiting from fast AF is so limited... shooting anything that moves from kids running around, people at weddings, photojournalism, sports, wildlife, street photography, etc. is much easier with phase-detection. No matter how good or fast the contrast-detect algorithms can be run, it still has to guess at the direction of focus adjustment, move the focus element a little, measure again, rinse and repeat. That physical process of the adjustment can't be overcome by faster processing.