The domino effect: Who will take Wallabies beyond 2019?

Wallabies coach Michael Cheika is reportedly subject of potential interest from English club Leicester Tigers. Ashley Western/MB Media/Getty Images

The biggest year of his coaching career is still to play out, but Michael Cheika's pending replacement at Australia's helm is as much a talking point as the Wallabies' Rugby World Cup fortunes themselves.

Cheika has already signalled his intention to finish up when the Wallabies' run ends in Japan, and he was on Wednesday linked with a return to the northern hemisphere, with Leicester Tigers, who find themselves in a relegation dogfight in the English Premiership, reportedly pondering a move for the 52-year-old Australian.

But there could be as many as five top Test jobs available after the World Cup; England, France and South Africa could all possibly be courting prospective replacements once the Webb Ellis Trophy is hoisted into the Yokohama air on November 2, if not before.

Only Andy Farrell [Ireland] and Wayne Pivac [Wales] are locked in beyond October and it may prove that once the first domino falls, the vacant All Blacks position being filled, the rest will follow.

For the Wallabies, that is New Zealand Rugby appointing Ian Foster as Steve Hansen's heir, as expected, meaning the likes of Dave Rennie and long-time Wales boss Warren Gatland may suddenly shoot to the top of Rugby Australia's list.

Stephen Larkham's demotion to a Rugby Australia academy and development coach has seen his stocks fall, particularly when Cheika had previously anointed the Wallabies great as the man to take over.

Pickings are otherwise slim on the domestic scene, with Dave Wessels, Dan McKellar and Brad Thorn all very much in the early days of their careers, while the vastly more experienced Daryl Gibson has re-signed with the Waratahs for one final year.

Jake White, meanwhile, was all set for a conference call with Rugby Australia as it mulled Cheika's immediate future after a miserly 4-9 return on the Wallabies' 2018 Test season. But it was aborted at the eleventh hour, as the governing body wanted to first complete its review; White also had little interest in filling the role in a short-term capacity.

White was previously close to landing the Wallabies job, after Robbie Deans' sacking in 2013, and just last year told ESPN that he would "never say never" if the Wallabies were to come calling once more.

But it appears that Gatland and Rennie will be the front-runners.

Rumours from France already have Gatland as Les Bleus' top target, while the Rugby Football Union won't rule out a play for the three-time Grand Slam-winning coach should Eddie Jones fail to lead England to glory in Japan.

Rugby Australia is unlikely to be able to compete with the money the RFU or French Rugby Federation could potentially offer Gatland; but he may forgo the extra euros or pounds sterling to be closer to his family in New Zealand, an opportunity the Wallabies job could provide.

But the rumours around Rennie seem to be gathering momentum. Rennie has played down suggestions that he could succeed Cheika as speculation, but he is another who would "never say never" if the situation were right.

The two-time Super Rugby-winning coach is a highly-respected figure in rugby circles, albeit one who has seemingly slipped down the pecking order in New Zealand, particularly with the meteoric rise of Crusaders boss Scott Robertson.

Rennie is contracted with Glasgow through to the middle of 2020, and ESPN understands the Scottish outfit is keen to retain his services beyond that point. But Rugby Australia may yet have an ace up its sleeve in Scott Johnson, who has worked with Rennie in his now-former role as Scotland's Director of Rugby.

Can Johnson sell Rennie on the challenge of the Wallabies? Has enough water passed under the bridge since the Robbie Deans era; a six-year term in which he failed to wrestle the Bledisloe Cup back from his homeland and that concluded with a 2-1 series loss to the British & Irish Lions?

Would Rennie instead prefer a role in Europe, one that keeps him in contention to coach the All Blacks down the track?

Each question is as important as the last, as with it shifts a domino that will change the coaching landscape of world rugby beyond the ninth staging of the Rugby World Cup.

So as the Nations Championship looks set to fall over without a tackle being made, the same can't be said for an international coaching scene that is set for its biggest shake-up in years.

And just like the World Cup itself, no-one knows quite just where the Wallabies will land.