Organisers of the Pro14 are in talks to increase the number of South African teams in the competition.
There is hope the new campaign net year will still involve South African teams alongside the best from Ireland, Scotland, Wales and Italy.
Cheetahs and Southern Kings have both featured in the Pro14, but the Kings will not be involved in 2020-21 following the club’s liquidation.
Negotiations will now continue as to which franchise will replace them.
A Pro14 statement said: “On August 25, Pro14 Rugby acknowledged under current international travel restrictions it is not possible for South African teams to fulfil Guinness Pro14 fixtures until 2021.
“Pro14 Rugby welcomes the news that the South African Rugby Union (SA Rugby) has been able to arrange a domestic schedule for its professional teams and that this is the first step in the return of their teams to on-field action.
“SA Rugby’s long-standing commitments are to field two teams in the Guinness Pro14 and in light of the withdrawal of the Southern Kings, discussions are on-going about fulfilling this agreement from 2021 using a replacement team from its current professional franchises.
“Additionally, both Pro14 Rugby and SA Rugby are in early discussions about potentially expanding the tournament and deepening our partnership to include more South African franchises from 2021.”