World Rugby boss Brett Gosper says a future World Cup could have more teams taking part without losing competitiveness.
The All Blacks captain Richie McCaw holds the Rugby World Cup. (The Webb Ellis Trophy). Photo: PHOTOSPORT
Both England 2015 and Japan 2019 will have 20 teams, but 2023 may be larger.
Gosper says allowing fringe nations into the event would allow them "to promote the sport in their countries".
A larger World Cup would offer the chance to sell the sport into new markets, as well as increasing the potential revenues from the tournament in terms of TV deals, sponsorship, hospitality and ticket sales.
Gosper says a larger World Cup would not necessarily mean teams playing more games, as tournament groups - which currently have five teams in them - could be juggled in size.
He says rugby union was growing strongly around the globe, but particularly in the markets of the US, China, India and Mexico, with Russia and Germany also growing nations.
Gosper says Rugby is the fastest growing team sport in the USA.
He added that although Germany and Russia also offered potentially huge new TV markets for the sport, 2019 was not considered the right time to expand and bring them in.
Meanwhile, Gosper says the buildup to this year's World Cup is going smoothly, with no major concerns, but a focus that "everything that needs to be done is done".