The smallest crowd in Wellington Sevens history threatens to shut down what was one of the most popular events in Kiwi sport.

New Zealand Rugby will announce in March whether the world series event will remain in the capital or if its 18th edition over the weekend will be its last.

Nigel Cass, NZ Rugby's manager strategic relationships and planning, says an unacceptably small crowd of about 10,000 was on hand for each of the two days.

That was well down on the average 14,000 last year.

In its hey day the 34,000-capacity venue would sell out within minutes, a primarily young crowd lured by a party atmosphere.

"We would need more people, ongoing, to make it viable," Cass said.

"Its not only commercial viability. Just for the atmosphere around the event we need more than 10,000 people."

A restriction of liquor rules, amongst other things, has changed the nature of the event.

Cass says a review over coming weeks will determine if the slide is irreversible at a tournament which still has two years to run on its hosting contract.

There is no chance of returning to the previous booze-fuelled approach, with society's attitude having moved on, Cass said.

Cass says other centres have previously shown interest in hosting.

However, options are limited by the logistics of getting 16 teams in and out smoothly, along with meeting the venue requirements of World Rugby.

"They play the other tournaments in iconic, global cities and stadia," he said.

"We need to have a city and a venue that sits alongside a Twickenham in London, Paris, Cape Town, Dubai and Hong Kong and so on."

World Rugby was happy with Wellington's running of the event and its innovations this year but officials have told NZ Rugby it is concerned about the empty seats.

"It might be that the fans have spoken and it's really tough to change," Cass said.

"But you don't walk away from 18 years, which on the whole has been successful, without looking under every rock."