"Industry leading ISO Performance" limited to 6400 native
High MP cameras is not about high ISO performance, it is about high DR at base ISO. If your applications require high ISO they don't require high MP, and then there's 5Dmk3 and 1DX.
If it will offer 12 DR stops @ ISO 6400 then why forbid them go so far?
I would be happy if it has 12 DR stops @ ISO 100, considering Canon's classic blown-out sky feature in the past.
Maybe they include ready to reuse half pictures with typical sky with a smart merge option - who needs the real sky?