World Rugby has confirmed it intends to hold internationals in the Northern Hemisphere from October 24 until December 5, meaning Ireland would complete their Six Nations schedule before participating in an invitational tournament with other European sides and potentially Fiji.
The body will propose the schedule at a meeting of its Council next Thursday July 30, as it seeks to hold the 2020 Rugby Championship in one host country - most likely New Zealand - from November 7 until December 12.
That could mean Munster will be without Springbok signings Damian De Allende and RG Snyman for the first round of the Heineken Champions Cup which is fixed for the weekend of December 12. Ulster could also be affected if Marcell Coetzee gets a South Africa recall.
If approved, the schedule would see Ireland's mens and women's sides complete their Six Nations campaign against Italy at home on October 24 and France away on October 31, with the other unplayed matches going ahead on that day.
The men's side will then get a weekend off, before playing in a once-off tournament involving the other Six Nations and two other teams. Georgia and Fiji are expected to make up the numbers.
The format has not been confirmed, but it seems likely that the eight teams will be split into two groups of four with a final weekend on December 5.
South Africa are not yet ready to throw their eggs into the European basket despite New Zealand Rugby announcing plans to abandon the current Super Rugby format from next season in a move that would threaten the long-standing SANZAAR alignment between the Southern Hemisphere heavyweights.
Irish rugby's hopes of restarting on the weekend of August 22 have received another major boost as the IRFU have confirmed that the second round of testing in Connacht and Ulster has produced 0 positive results.