The Swans still have co-captains Adam Goodes - currently leading Australia into battle against Ireland in the International Rules Series - and Craig Bolton.
But Jack, 23, believes there are plenty of rising leaders at the Swans and new coach John Longmire could select a younger replacement for Kirk should he see fit.
"One of challenges we faced this year when we knew Kirky was leaving was trying to find that next tier of leaders to come through," he said in Limerick this week.
"Players that have been at the club five, six, seven years really need to learn off those players and now it's time to step up.
"There are some up and comers like Jarrad McVeigh and players like that who are really stepping up their leadership qualities.
"Whether John wants to appoint someone else or stay with the two, it's entirely up to him."
Longmire has taken over from premiership coach Paul Roos and will lead the club into 2011 in what will be a new period for the Swans.
The players won't be unfamiliar with Longmire, given his presence at the club in an assistant role and later coaching co-ordinator since 2002.
Jack says he expects Longmire to take a relatively similar approach as Roos, and for the defensive nature of the Swans' game plan to continue.
"I think the fundamentals will stay the same and he has already made it public that there will be a few structural changes, so that will be exciting," he said.
"It's fresh for the new blokes who are there and it's fresh for blokes like me who have been there for four of five years.
"With a new coach coming in and new players coming in, hopefully we can start to build something for the future.
"I'm sure he definitely has some new ideas under his sleeve but he is really strong on the defensive side of the game like Roosy was."
Jack, Goodes and McVeigh are all in Ireland as part of the 23-man International Rules squad playing Ireland in a two-Test series.
The touring party moved to Dublin on Monday to prepare for game two at the famous Croke Park.
