The Nikon Keymission 360 will cost $499 and will be available on October 26, 2016 in the US, according to an Amazon listing spotted by NikonRumors! The listing has since been removed.
UPDATE: This rumor proved to be correct. The listing is back on Amazon, for $499.95, with an availability of October 26. It’s also available from B&H with a free shipping and a free accessory pack worth $150. I’m not yet sure if the Amazon preorder includes the accessory pack.