I consider 1" format as sweet spot of still/video camera. I enjoyed J1 and 10/2.8 combo very much. An AW body with this dedicated wideangle zoom can be good reason to make a return to Nikon 1. And yes, the long term support is essential.
As for the fisheye, I'm personally sold by the stereographic design employed by Samyang. I would go for a sper-wideangle with Nikon 1, because Nikon would employ the conventional equidistant design.