The best arrangement is for the Pro14 to revert to Pro12, and South Africa to hold its own 8 team domestic competition perhaps including Argentina's Jaguares. The best four South African/Argentine teams then qualify for the European Rugby Champions Cup with the other four going into the Challenge Cup. In all honesty I think there is little interest in South Africa in playing Zebre, Dragons, Edinburgh, etc.
This would be really cool. But would need the European qualification