Foran was injured while making a tackle on James Graham early in the test, damaging the same shoulder which required surgery three years ago.
Foran - who also had highly publicised off field issues - has struggled to put a run of games together over the past four years at the Eels, Warriors and Bulldogs.
The problem for Foran is that he is out of contract at the end of next year, and injury problems may make it hard to find a new contract.
He had only just returned to the Kiwis, replacing Shaun Johnson who was dropped after a nondescript display against the Kangaroos.
Kiwi coach Michael Maguire said after the test victory: "I'm shattered for Kieran. He is one hell of a fella, he put himself back in this arena.
"No doubt he will get back to work and do what he does best which is get himself right. He was in really good shape for this game.
"We were really excited for him as a group. To see him go down was devastating."
Veteran NRL and British coach Wayne Bennett has called on the NRL to investigate why bad shoulder problems are so common.
"I think, without making the headline, that it's the most common injury at the moment that we have," the Souths' boss said.
"It's something to look at — why so many of these type of injuries are happening and why it's finishing guy's careers a lot earlier than we all thought they would."