I don't think it will be Williamson. With the likes of Young, Chapman, Bruce, Dale Phillips, Severin, Kelly, the O'Donnells, Foxcroft, Heaphy, Abbas, Mariu, and Hugo "GOAT wonderkid" Bogue etc. all waiting in the wings NZ has clearly far more batting depth and strength than India and Australia, so thus there is more competition for KDub's spot than for Kohli's or Smith's.
And besides we've won series in England (rested) and India (injured) without him, so we probably won't need Kane when we win in Australia in a couple of years