The Rugby Football League wants the Millennium Magic weekend to become an annual fixture but has revealed Super League clubs will have the final say.
The weekend in Cardiff proved a big hit with supporters
The inaugural event drew more than 58,000 fans to Cardiff, prompting RFL executive chairman Richard Lewis to hail it as a "tremendous success".
"All the feedback we've had so far has been very positive," said Lewis. "I'm sure the decision will be to go ahead."
The event is pencilled in for two more years, with Cardiff to remain the host.
"We've got an agreement with Cardiff that, if Millennium Magic happens, it will be in Cardiff," added Lewis.
"It's almost certain that it will be on for the next two years and way into the future but we are not in a position to confirm that yet."
Initial estimates claim more than 10,000 people from in and around Wales attended the two-day event.
I know they're talking about Ireland and Scotland and I think it's good to take the games to places where it's tough to reach
Bradford captain Iestyn Harris
The encouraging turn-out boosts the chances of a Welsh Super League franchise in 2009.
It also builds on the interest generated in the Principality by the decision to stage the Challenge Cup final at the Millennium Stadium between 2003 and 2005.
However, the RFL says it is considering taking the event on the road in the future, revealing that representatives of both Dublin and Edinburgh attended the two-day event in Cardiff.
"They've been very impressed by the concept," said the RFL's chief operating officer Nigel Wood, who came up with the original idea.
"They went about the city and saw the number of supporters and how much they were enjoying themselves. But they came to observe - our commitment is to Cardiff at the moment."
Bradford stand-off Iestyn Harris, who played rugby union for both Cardiff and Wales before returning to league, gave his unqualified backing to the concept.
"To get 58,000 was pretty good," he said.
If they decide to do it again, I hope the fans will come out and really support it
Leeds skipper Kevin Sinfield
"It is difficult to get the stadium full and there were people coming and going all the time but I thought everybody made the weekend a credit to rugby league and I think the games were of a high quality.
"I know they're talking about Ireland and Scotland and I think it's good to take the games to places where it's tough to reach."
Leeds captain Kevin Sinfield, who played in the Cardiff Cup finals of 2003 and 2005, said: "It was a bit strange compared to the two finals.
"It was a little bit empty but it's a start for everybody. The concept is fantastic and, hopefully, we can build on it and fans can get really behind hit.
"Sometimes you have to have a trial run.
"If they decide to do it again, I hope the fans will come out and really support it, fill the stadium and make it really special for all the teams that are playing in it."