Larkham confirmed on Friday he will relinquish his Brumbies duties at the end of 2017 after signing a deal to become a full-time Wallabies assistant.

The World Cup-winning flyhalf has been living a double life as a Brumbies mentor and Wallabies assistant for the past 18 months and said the role had become "unsustainable".

His decision to join the Wallabies in a full-time capacity is a blow to the Brumbies' leadership stocks, with the club already with Stephen Moore, David Pocock, Matt Toomua and Christian Lealiifano.

But Larkham, who turned down a chance to be the Brumbies' long-term coach, has backed a new generation of players to rise to a new level next year.

Asked if the 2017 campaign would be a rebuilding year, Larkham said: "If you look at where the Brumbies came from [in 1996] everyone had written us off and we enjoyed that.

"I'm not saying we've been written off next year. We've still got a very strong squad for next year because a lot of guys have gained experience.

"I think there's good excitement going into next season. I don't see it as a rebuilding phase, I see it as a real opportunity with good excitement.

"I genuinely feel the players we've recruited will combine into a fantastic team next year. It's not about [me winning a title], it's about the collective effort.

"I just know the Brumbies are in a good space at the moment, I've got confidence they'll get to where they need to be in the future."

The Brumbies will have a 12-month transition period to find Larkham's replacement.

Some resumes started filtering into Brumbies headquarters on Friday after Larkham's decision was made public.

Brumbies assistant Dan McKellar will be a contender while former coach Laurie Fisher and ex-assistant Matt O'Connor could also feature.

The process will likely be put together over the coming months but the worldwide search is unlikely to begin until a new chief executive is appointed.

Larkham is being groomed as a future Wallabies mentor and is already the frontrunner to replace incumbent Michael Cheika after the 2019 World Cup.

His new Wallabies job will allow him to be based in Canberra without the pressure of running day-to-day Super Rugby operations and he hasn't ruled out a return to the Brumbies in the future.

Larkham says his loyalties were divided between the Brumbies and the Wallabies, having tasted Super Rugby and World Cup glory with both teams.

"I reflected on how difficult it was to do both jobs for my wife and young family and realised it was unsustainable," Larkham said.

"I had to make a decision and it took a while because I'm a loyal person and I've got loyalties both ways to the Brumbies and the Wallabies.

"This gives me an opportunity to commit fully to the Brumbies [in 2017] and I'm still doing that next year and looking forward to it.

"I've learnt a few lessons ... the offer with the Wallabies through to the World Cup allows me to stay in Canberra.

"The World Cup is the pinnacle of world rugby and I think this next build up will be a great journey."

Larkham and the Wallabies flew to Europe on Friday afternoon to start an end-of-year grand slam tour.

He is working to add at least two more players to the Brumbies roster after Robbie Coleman's defection to the Western Force and Christian Lealiifano unlikely to be able to play as he continues his battle against leukaemia.

Lealiifano will go to Melbourne over the coming days to start his next chemotherapy treatment before having a bone-marrow transplant.

Larkham has been with the Wallabies since August and won't return to Brumbies duties until mid-December.

"I'm going to put everything into this season, but it's not about me. It's about the team evolving and being better than what we were last season," Larkham said.