Ioane, who has been formidable this season with the Queensland Reds and Australia, fractured his thumb in the Wallabies' opening 32-6 victory over Italy at the weekend and will miss the remainder of the pool stage at least.
Coach Robbie Deans has several options to replace Ioane for this weekend's match against Ireland, including Drew Mitchell, who scored seven tries at the last World Cup, and James O'Connor, who came off the bench to great effect against the Italians in Albany.
"Digby's a world-class player and he gets over the advantage line more often than not, so it's a big loss," scrumhalf Will Genia told reporters on Tuesday.
"But we have players like Drewy (Mitchell) and obviously James coming back into the starting line up as well. We'll see what Robbie wants to do but I'm sure they'll be some quality players to put their hands up."
Not only was Ioane bookmakers' favourite to finish the tournament as top try scorer but he also played an integral role in Australia's backline defence, covering for Quade Cooper in the flyhalf position.
"Whoever jumps in on the wing will have to defend that first channel," Genia added. "Whoever it is, they are all good tacklers, good defenders."
Genia said Ioane, who will stay with the squad and undergo surgery, was still confident of being part of the Australian campaign to win a third World Cup later in the tournament.
"He's a bit upset but he's a positive guy and always got a smile on his face," said the 23-year-old, who plays with Ioane at the Super rugby champion Reds.
"He's just looking forward to getting the chance to play again."
Adam Ashley-Cooper was once the most notably versatile of the Australian backs but he said there were now several others with the flexibility to be able to cover for the "massive blow" of Ioane's injury.
Normally a centre, Ashley-Cooper scored Australia's second try after starting on the wing against the Italians last Sunday and said he would be happy to play in any position as long as he was in the starting 15.
"I guess losing Digby throws a spanner in the works and I'm sure they'll be a few players unsure of where they will be playing this week," he said
"The beauty of who we've got in this squad, the backline players, is there are not many specialists, we've all got a bit of the utility tag.
"We've got the talent and the depth to cover any position and that will hopefully pay off when it comes to losing Digby."