A top New Zealand official says Warren Gatland is among the potential candidates to succeed Steve Hansen as the All Blacks’ head coach, particularly if the British & Irish Lions achieve a stunning series win. New Zealand Rugby’s chief executive, Steve Tew, has also said the visitors remain a serious threat in the Test matches and, even if they lose heavily, that the future of Lions tours will not be endangered.

The experienced Tew, whose spell at the helm of NZR has coincided with the All Blacks winning back-to-back World Cups, has acknowledged that assistant, Ian Foster, is in pole position should Hansen confirm his intention to step down after the 2019 tournament in Japan. If New Zealand were to suffer an unscheduled wobble, however, Tew anticipates Gatland’s name entering the frame.

“Ian Foster is sitting there as a very strong candidate when Steve does finish but there’ll be others,” said Tew, suggesting that the overseas-based Gatland, Joe Schmidt and Vern Cotter would be potential alternatives. “Joe is sitting in Ireland and we’d like to have him back. Vern is coaching at a very high level and you wouldn’t rule Gatty out either.”

Asked whether Gatland’s stock would rise appreciably if the Lions won the Test series, Tew replied: “You’ll have to ask Warren what he wants to do next. We don’t know what Steve’s doing yet but what we will do is manage the transition very well. We’ll be sitting down later this year to work out the process.”

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The notion of Gatland taking over from Hansen might sound improbable to many in New Zealand but there is considerable respect for his successful stints in charge of Wales, Wasps and the 2013 Lions in Australia. “I’m still of the view this is a very good Lions team and once they get together they’ll be very tough in this Test series,” said Tew.

“I think the physical attrition of the series is going to take its toll. One team will come through that better than the other.”

The commercial benefits to New Zealand Rugby of staging a Lions tour are similarly striking and, unsurprisingly, Tew wants his country to host another in 2029. “It’s unique and something that’s worth preserving. The current contract between the Lions and Sanzar (South African, New Zealand and Australian Rugby) runs out after this tournament and needs to be renegotiated but the commitment from all of us is that the Lions are locked into the calendar.”

More contentiously he has dismissed switching to a 16-year cycle to allow Argentina, now part of the Rugby Championship, to host the Lions before 2033 at the earliest. “We’re not currently anticipating Argentina coming into it because there’s a history of them touring to the three countries.”

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World Rugby’s vice-chairman, Agustín Pichot, feels otherwise, with the possibility of arranging early tour games in North America clearly an option, but the three leading southern hemisphere unions are, to varying degrees, kept financially afloat by the Lions. “In 16 years time it might change but I think you’d struggle to run a Lions tour with a meaningful schedule in Argentina,” said Tew. “There’s no doubt our good friend Mr Pichot has his eyes on the Lions but I don’t think that would involve turning it into a 16-year cycle. That’s not on our radar.”

Nor, predictably, is backing a Super Rugby franchise in the Pacific Islands – “In the immediate future I can’t see how you could sustain a professional team in a Pacific Island unless, financially, there’s significant private intervention” – but as recently as the past week Tew has had discussions with South African officials about rugby’s future viability across the southern hemisphere. “It’s not as simple as saying they [South Africa] want to leave Sanzar. I’ve asked that question in the last week. The complication for the southern hemisphere is that we all live so far apart. It’s an enormous cost.

“One of the things we’ve learnt [from Super Rugby] is to be careful about expansion. The Aussies, the South Africans and to a degree the Japanese are learning that the hard way.”

Tew has reaffirmed the All Blacks will continue to play financial hardball when it comes to negotiating deals to play Tests in the northern hemisphere. Despite not having agreed to play England on tour this autumn, discussions with the RFU’s chief executive, Ian Ritchie, proved informative. “We know that when we play at Twickenham you can ratchet the turnstiles up. Ian and I had a good commercial conversation so I’ve now got a good idea what the real number looks like. We certainly had a conversation about a fee that was higher than we’d ever had before. That’ll sit in the system until the next time we come back and discuss it.”