the crank on the left... if an adaptor with a larger handle could be mounted for easier turning then all you'd need would be a lens and a bunch of cards as power would not be a problem. perfect for long trips or places where electricity is not accessible.
what i'd really like to see and nobody else has done is reintroduce the film advance lever! if this was a dslr, instead of the mirror assembly running on motors and using power, the film advance lever could crank and recrank the mirror. on a mirrorless, it could be some other type of switch or toggle, another way to charge the battery, or the usual 'crank it per picture' feature to enhance the retro aesthetics.