The WRU announced in October three licences would be granted – one to a team in Cardiff, one in the west and one in the east.
Negotiations have continued with Ospreys, Scarlets, Cardiff and Dragons but nothing will be resolved on this issue before the end of the year.
If an agreement cannot be reached in January, a six-month tender process could open to determine the successful trio.
It seemed there would be a straight shootout for survival between Scarlets and Ospreys for the west licence before another proposal emerged.
The WRU took over Cardiff in April after the organisation slipped into administration.
The governing body has since been looking for new investors, with Ospreys owners, Y11 Sports and Media, linked to buying Cardiff, enabling the WRU to get to its magic number of three.
The WRU and Y11 have both declined to comment, fuelling the fears of Ospreys supporters about the survival of their team, while Cardiff fans have been vocal on social media against any such takeover.
“Work has continued to secure a sustainable long-term future for the Cardiff club and its supporters,” said the WRU.
“This is a significant decision and will be taken with the thorough scrutiny and due diligence it deserves.”
The WRU also wants control over playing affairs at the surviving three sides while still asking backers to put money into the ventures.
That issue has also provided a major stumbling block in negotiations and delayed the process.