Earlier today, South African Rugby confirmed that the Southern Kings and the Cheetahs will not play in Super Rugby next year.
The news means that the South African federation have two professional teams, but have no league for them to participate in. They may not last long without a league, with persistent reports of an entry into next season's Pro12.
Although the season is due to begin in September, no fixture list has been revealed. Created as the 'Celtic League' in 2001, the modern-day Pro12 is used to teams joining and leaving in it's relatively short history.
Of the four countries that have had teams in the league, only Ireland have not made any changes. Since the opening season in 2001, Connacht, Leinster, Munster and Ulster have all competed in the league.
The biggest change has come from Wales. In the opening two seasons there were nine clubs from the Principality, counting for over half of the teams in the league. Bridgend, Caerphilly, Cardiff, Ebbw Vale, Llanelli, Neath, Newport, Pontypridd and Swansea all competed to various degrees of success.
At the start of the 2003-04 season, the Welsh Rugby Union introduced five regional sides to replace the nine clubs. Cardiff Blues, Dragons, Ospreys and Scarlets all survive to this day, but the Bridgend-based Celtic Warriors only lasted one season.
In Scotland, there has been relative stability with the ever-present Edinburgh and Glasgow. In the second season of the Celtic League, Border Reivers were introduced but only lasted five seasons.
Italian sides took their place in the Pro12 in 2010. Treviso remain in the league to this day, but Aironi were replaced after two seasons by Zebre.
24 teams have played in the league under its various guises since the start of the 2001-02 season, but only those 12 remain.
After the first four seasons of the Celtic League saw a different amount of teams compete each season, there has been relative stability since Italian sides joined in 2010.
The potential arrival of Southern Hemisphere teams into the league will add a new dimension to proceedings, but that's nothing new for the Celtic League/Pro12. It has always thrived with change.