Piutau, still only 23 and with 14 caps, is a player the All Blacks definitely didn't want to lose.
But it is understood he has been offered an incredible deal to play in Ireland with Ulster and has already signed. He is believed to have been persuaded that he can emulate Kaino and enjoy a lucrative overseas stint and then pick up his All Black career once he returns before the 2019 World Cup.
The national body has long known that several senior All Blacks will call it quits after the World Cup. Veterans Dan Carter, Ma'a Nonu and Conrad Smith have confirmed they will play club rugby in France after the tournament.
Richie McCaw has hinted he will probably retire - a fate that is thought to be most likely for Keven Mealamu and Tony Woodcock as well.
But Piutau was not a player the NZRU had initially thought was in danger of defecting after the tournament. His departure is understood to have caught everyone by surprise as the All Black coaches have been clear that they see him as a player with considerable opportunity this year but more so next if he stayed.
He's competing for a place in the All Blacks' back three with Ben Smith, Julian Savea, Cory Jane and Israel Dagg.
The best case scenario for those players is that there will be room for only four of them in the 31-man World Cup squad. Smith and Savea are both certain starters and the All Black selectors will probably have to make a choice of eliminating Jane, Piutau or Dagg.
Arguably, by the end of November last year, Dagg was the player who appeared most vulnerable. The selectors have said they want players with versatility, which is something Dagg doesn't necessarily bring as he is viewed as a specialist fullback and ranked behind Smith in that role.
Piutau, on the other hand, is equally comfortable at wing or fullback and has even played centre for the Blues this year.
His ability under the high ball, pace, elusive running and incredible ability to stay on his feet in contact are qualities that will be valuable later this year in England.
All Black coach Steve Hansen has not previously penalised players who have decided to play overseas. He has been happy to pick anyone who is eligible regardless of what decisions they have made about their longer term future.
That was the case with Hansen's predecessor Graham Henry until 2011. Henry, with his assistants Hansen and Wayne Smith, decided that in World Cup year it was important, where relevant, to back those players who had shown a desire to stay in New Zealand beyond the tournament.
Hansen hasn't yet said whether he will adopt that same policy in this World Cup year.
Player retention is a constant battle for the NZRU - and one it felt it was winning having locked in the likes of Kieran Read, Sam Whitelock and Ben Smith until 2017.
Kaino's signature - he is staying until 2018 - was another major victory as the Blues captain will inevitably take more of a leadership role in 2016 with McCaw, Smith, Carter and Nonu all departing.
Brodie Retallick, Julian Savea, Colin Slade and Sam Cane are also off contract at the end of this year. All four are considered long-term All Blacks and vital to the cause.
Retallick, Savea and Cane are all expected to confirm that they will be staying until at least 2017 but Slade has said he may keep his options open.
Piutau's departure - what it means
• Possibly puts his World Cup place in jeopardy as the selectors may favour those who have committed to stay beyond World Cup.
• Endorses the idea that players can leave New Zealand in the early part of a World Cup cycle and re-integrate in time for the next tournament.
• Leaves the Blues short of an inspirational talent around whom the backline could be built.
