I wouldn't hold out much hope for the 808's sensor in Nokia's flagship WP8 device. If you've seen reviews of the 808 then you'll have seen how thick it is compared to the iPhone 4(S), Galaxy SIII and HTC One X. To be blunt, the 808 is a brick. More than likely, the flagship WP8 handset will have Pureview technology and a lower resolution sensor (12MP? 16MP?) to maintain a sleek form factor while giving the handset imaging prowess that's a cut above the direct competition. Of course, it is possible that they would do another high-end handset with the full 41MP sensor on board.
Truth be told, while I love the idea of the 808 I really can't see me buying a device like it purely for form factor reasons. The 710 is already a bit too thick with the official case on; you KNOW when it's in your pocket.