World champions South Africa have committed to the Rugby Championship until 2030.
The Springboks withdrew from the 2020 tournament because of fears over player welfare amid the Covid-19 pandemic.
There have been reports South Africa were looking to join the Six Nations in 2024 after the next World Cup.
But South Africa Rugby says it “welcomes” plans to restructure the tournament, which also includes New Zealand, Australia and Argentina.
“We are looking forward to seeing what the new strategic plan for the competition entails, with possible international expansion on the cards,” said the governing body’s chief executive, Jurie Roux.
Rugby Championship organisers Sanzaar (South Africa, New Zealand, Australia and Argentina Rugby) said the home-and-away format will be replaced with a “mini-tour” schedule.
Under the revised format, a team will host another nation for two matches one year, before playing an away double-header against them the following year.
“The re-commitment by the four unions to the long-term future of the international game is an important start as we embark in a new direction for both the unions and the organisation over the coming years,” said Sanzaar chief executive Andy Marinos.
In the absence of 2019 Rugby Championship winners South Africa, the remaining teams are playing a Tri Nations Series this year, which began on 31 October when New Zealand beat Australia 43-5 in Sydney.
In September, South Africa’s four Super Rugby sides started exploratory talks about joining an expanded Pro14.
The 2020 Super Rugby season was cancelled because of the coronavirus pandemic, with New Zealand, Australia and South Africa each having their own domestic competitions for this year.
“Although we had to change our domestic focus, we still have a long history with the All Blacks and Wallabies, as well as a long-standing friendship with the Pumas, and we look forward to more world-class Test rugby,” added Roux.