http://www.stuff.co.nz/sport/cricket/8187187/Black-Caps-opening-pair-is-anyones-guess
This article seems to suggest that: McCullum will drop, Taylor will be back, Watling will stay #6 & Keep, Brownlie did enough to keep his spot, and Fulton will open. If you assume Taylor at 4, Brownlie 5 & Watling 6 then you have McCullum at 7 or 3, meaning we either would have only 3 seamers, Williamson opens, or Williamson is dropped.
No matter how this turns out I am going to be baffled by the batting order that lines up in the first test I think. Someone is going to miss out, especially if McCullum is in the middle order as well.