Wynne Gray: Hansen's dilemma - When to call it quits

When Steve Hansen identified 2017 as the likely end to his All Black coaching career, it came with a strong plea.

He thought the All Blacks would benefit if they changed their head coach midway through a World Cup cycle. His rationale?

"I think when people come in, it is easy to get some really dramatic shift early on and it's a lot harder to keep that momentum going," he said.

"I like the idea of changing guard halfway through a cycle which has a World Cup in the middle of it."

Since Hansen's comment after last November's World Cup triumph, he has mellowed a touch to say he's "50-50" about coaching the All Blacks to the Rugby World Cup in Japan in 2019.

Captain-in-waiting Kieran Read has slipped his thoughts into the conversation hoping Hansen will stay in charge until the next World Cup.

Hansen has this year to rework his All Black squad en route to New Zealand hosting the Lions in 2017 and the probable fullstop on his All Black coaching term.

Should Hansen be tempted or persuaded to extend that contract he will be totally comfortable about that choice. He will not be pressed into something he is not fully committed to.

If he agrees to take the side to the 2019 Rugby World Cup, will Hansen then be nudged towards a 2021 finish date? That would fit in with his theory about it being best for countries to change coaches midway through a World Cup cycle.

Either way it is a big call for Hansen who has been coaching at international level since he started with Wales in 2002.