Gregor Paul: The dark cloud hovering over Black Ferns' triumph

New Zealand perform the Haka after winning the 2017 Women's Rugby World Cup. Photo / INPHO Dan Sheridan.

The Black Ferns sit atop the rugby world and yet looking down from their summit, they might wonder what level of optimism they can have about their future.

They might wonder whether they even have a future as a high-performance team such is the pressure in the global women's game to grow sevens.

The question of whether rugby executives in the leading nations are willing to invest in both women's XVs and sevens has become the dark cloud hovering the Black Ferns World Cup-winning parade.

The Black Ferns suspect it is probably going to rain - that for all the feel good that was generated at the recent World Cup in Ireland and for all the support the tournament gained, the tide has already turned when it comes to XV-a-side in the women's game.

Maybe it's already a dead duck - that too many nations have already decided they no longer care about it and are going to through all their eggs in the sevens basket.

Global attention was certainly grabbed at last year's Olympics when all 16 teams in Brazil showcased the quality of women's sevens rugby.

It was easy to see on the back of two thrilling days at Rio why so many countries are opting to invest all of their available resources into sevens.

The fact the gold medal was won by Australia strengthened that conviction.

Over the Tasman, they have almost given up entirely on the women's 15-a-side game.

It is barely resourced as the decision was made to throw the kitchen sink at sevens.

Inevitably as Australia have become such a force at sevens, they have regressed in XVs, finishing sixth at the World Cup and also having taken some frightful hammerings from the Black ferns in recent encounters.

But sacrificing one version to excel in the other is an increasingly common strategy.

Sevens is in the Olympics, it has a world series up and running and a wider base of genuinely competitive nations with plenty more investing enough to imagine they will be a handful come the next Olympics in 2020.

Sevens has won not just hearts and minds in the women's game, but also the lion's share of investment.

It's growth forecasts are impressive on every front.

More female players are taking to it, more nations are getting into it and corporate interest is warming up.

The future of sevens is bright, but not so much for the women's longer version of the game, despite the profile and buzz the Black Ferns are currently enjoying.

Who would know why it turned out this way, but the perception grabbed hold a few years ago that 15-a-side rugby, all the way up to international level in the women's game, is not driven by a high-performance culture.

Even in New Zealand that has been a hard perception to break among rugby executives which is illustrated to some extent by the hybrid funding model currently in play.

In a four-year investment cycle, the majority of the overall budget allocated to women's rugby in New Zealand will be invested in sevens.

The XV-a-side game takes a bigger share in World Cup year - which is thought to be largely the case in England, France, Canada and the USA.

The great hope for all those women who played in Ireland is that the respective speed, skill and intensity of the rugby was of a high enough standard to persuade the relevant decision-makers that the female game can have two meaningful, highly marketable and sustainable strands.

They hope they have gone some way towards killing the prevailing attitude that when it comes to women's rugby it is one or the other - sevens or XVs - not both.