However, ifs and buts can't come into that decision. Bridges get crossed as and when needed.
An outsider if problems arise with Read? The new No 7, Sam Cane. He's already captained the All Blacks at the World Cup, has the support of the coaching panel and looks the man in waiting further down the line.
Kane Williamson will be McCullum's replacement, barring any desire to keep his focus on his batting, at which he sits top of the test world. He's already confirmed to lead the team to the world T20 in India in March.
The only alternatives are wicketkeeper BJ Watling, who appeals more as a lieutenant; opener Tom Latham has his supporters, again further down the line; and senior bowler Tim Southee, although fast bowlers rarely get the captaincy.
So two sports have lost a leader, but seem well placed to carry on, with different personalities at the helm. Both very much set for business as usual.