Ranked a lowly eighth in the world two years out from Australia's hosting of the 11th global showpiece, the Wallabies will need something special to lift the Webb Ellis Cup for a third time.
Horan reckons that X-factor can be the code-hopping Suaalii, who continues to dazzle after making a spectacular man-of-the-match Test debut against England on last year's grand slam spring tour of the UK.
"Rugby World Cups, you can identify with certain players - Jonah Lomu in '95 and David Campese all those years ago in '91 and Joseph Suaalii's got the chance to do that," Horan told AAP.
"He's an athlete first and a footy player second and he could play three or four positions in the Wallaby backline and still be outstanding.
"So there's still a couple more years to go and he's really learning the game of rugby now and it's a great opportunity for him to be the star of the Rugby World Cup 2027."
The two-time World Cup winner's glowing endorsement of Suaalii aptly came on the day the late Lomu would have turned 50.
And Sonny Bill Williams fully agrees with Horan.
Having also switched from the NRL to the 15-man code, Williams was instrumental in New Zealand's own Rugby World Cup triumph on home soil in 2011.
Now he believes Suaalii may well be the game's premier player when the World Cup kicks off October 1, 2027.
"Anything's possible," Williams told AAP.
"He just needs a bit of time. You can play him anywhere - 13, wing or fullback. For myself, I like him at 13 with more ball in his hands in the air.
"But he's a type of player that you can change the game plan around.
"He's like Izzy Folau when he came into the scene, so it's exciting times."
Suaalii is recovering from a sickening head knock suffered in the NSW Waratahs' Super Rugby Pacific loss to Queensland last Friday night.
With the Tahs needing to win their last three, tough games to squeeze into the finals, Suaalii has been advised to abort his Super season altogether and freshen up for the showpiece British and Irish Lions series.
But Wallabies coach Joe Schmidt doesn't subscribe to that approach and hopes to see his chief strike weapon back on the pitch ASAP.
"I'm keen to see him keep playing," Schmidt said.
"He's missed a few games already this season. He hasn't had that many games anyway so, for Joseph, it's important that he just keep playing when he's fit and available to play."
Schmidt also has no issues with Waratahs coach Dan McKellar deploying Suaalii at fullback after he played outside centre on the spring tour.
"I'm really happy that Joseph plays wherever Dan needs him to play," he said.
"Dan and I have had the conversation. Dan actually asked me, 'Do you want me to play him at 13?'
"And I said I just want him with his boots on, playing the game.
"One of the beauties of playing 15 is you see the whole game in front of you, and Joseph has had that opportunity.
"But, then, they don't use him like a normal 15 either. He comes into the front line on some set plays and ends up in the front line on occasions.
"The try against the Brumbies - 15s don't usually take flat balls off lineouts and things like that.
"It's just great to see him out there and playing and I thought he was going really well until he got that knock in Friday's game.
"But he's OK, and that's the main thing going forward."
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