The Cheetahs and Southern Kings have competed in the competition since 2017, though the latter will be replaced in 2021 after being put into liquidation by SA Rugby.
"SA Rugby's long-standing commitments are to field two teams in the 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," PRO14 Rugby said in a statement.
"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."
The Cheetahs and Kings have been forced to withdraw from the 2019-20 season due to travel restrictions brought about by the COVID-19 pandemic.
SA Rugby chief executive Jourie Roux confirmed to reporters previously that the union is looking at options outside of Super Rugby for its domestic teams. Talk of moving away from playing Australasian and Argentine teams in favour of European opposition has been mooted for some time.
"Ultimately, we can't project what rugby will look like in years to come, and to do that would be very bold and brave because the only thing you can be sure of is that there will be change. I wouldn't be doing my job not to look at Plan B or Plan C," Roux said.
The attraction of Europe to SA Rugby is its lucrative television market, similar timezone and ease of travel that will help with player welfare.
The PRO14 contains teams from Ireland, Scotland, Wales and Italy.