Rugby Union Players' Association boss Ross Xenos has implored the ARU to push for a 'Plan B' for under-threat clubs the Western Force and Melbourne Rebels.

The Rebels played on Friday night and the Force play on Saturday, with neither knowing for sure whether it would be their final outing as a club.

Xenos, in an article on the RUPA website, said with South Africa's clear, burgeoning interest in competing in European leagues, Australia had to consider more options.

South Africa's two axed Super Rugby teams - the Cheetahs and Kings - will live on in Europe's Pro12 from 2018-19 and beyond, and there has been reports other franchises are also interested in such a move.

Europe's timezones are more friendly for South African viewers, with less travel to combat as well.

Australia's unlucky team, however, will not have an alternative route to keep its brand alive, Xenos said.

"It is becoming increasingly clear that SARU are planning on spending the next three years determining where they will be best suited long term," he wrote.

"They are establishing ‘proof of concept’, as they have put it, to either continue in partnership with SANZAAR or instead play in competitions which are far more suited to their time zone."

Zenos said a move to push for a 16-team Super Rugby competition until 2020 would re-open the door for a trans-Tasman competition should South Africa depart SANZAAR, a competition format for which RUPA has been a vocal advocate.

"Keeping all five teams alive through to the end of the current broadcast agreement in 2020 gives Australian Rugby the chance to build towards a Trans-Tasman competition as an equal partner with New Zealand," he wrote.

"That is the competition that can deliver the seismic commercial and competitive shift that the game requires to sustain Wallaby success and drive revenue growth to implement bottom-up engagement strategies."