Milligan, whose international career stretches back 13 years before the 2006 World Cup, has made 79 appearances for his country.
The 33-year-old captained Australia at the 2019 Asian Cup in the United Arab Emirates. But he turns 34 next month and with the Socceroos gearing up for the qualifying phase for the 2020 World Cup in Qatar, he is unsure if he will keep wearing the green and gold.
“Everything at the moment, all the conversations I’ve had with Arnie are quite short-term,” Milligan told The World Game.
“I’m not really not too sure what the future holds to be honest. I’ll see how we go this season, I’ll see how the next camp rolls around and I’m sure a discussion will be held there again.
“While I very much enjoy playing for the national team, and I still feel I bring enough to help out, and as long as Arnie and the staff feel the same, then that will be where we sit.”
Milligan sat out the Socceroos’ recent friendly against South Korea, along with a lot of regular starters such as Mat Ryan and Trent Sainsbury.
Earlier this month the midfielder joined English League One club Southend United after leaving Scottish side Hibernian.
Considering League One clubs play 46 matches in a season, along with cup competitions, Milligan believes the move to Southend will keep him sharp and match-fit.
“I’ve had a lot of talks with Arnie about what both of us want, but that [the amount of games] definitely helps in the immediate future with the Socceroos,” he said.
Milligan has already made several appearances for Southend in pre-season, featuring in friendly matches against Reading and Billericay Town. The club is currently in Dorset on a training camp and will face Dagenham & Redbridge this Saturday and then Millwall next week in friendlies.
“It’s been good, it’s a very good club,” the defender said.
“It was something that I wasn’t really sure what I was going to do to be honest. There was a few things to weigh up but after meeting the chairman and Kevin, I think it became clear to be that this was a good fit and that’s all been reconfirmed since I’ve arrived here.”
Southend struggled last season, finishing 19th and just missing the the drop down to League Two. The Essex club is keen to avoid a repeat with 11 players replaced with four new signings.
Milligan is confident the Schrimpers can move up the ladder this season and be competitive.
“Quite a few players have left from last season,” the 33-year-old said.
“Kevin and the chairman are still in a bit of a rebuilding phase but they do want to do well.
“We haven’t sat down specifically and set goals yet, but he’s shown his intent in what he wants to do with players that he wants to bring in and players that he has brought in.
“They definitely want to be successful and that was a big drawing point for me. Knowing Kevin, and what he’s done in the past, I don’t think he’ll settle for anything less than competing well.
“I’ll just do my part and help out where I can. The way that I play is not going to change the club or anything like that, but I think they know and the main reason they got me is they know what they’re going to get.
“It will definitely help.”
Australia will participate in next year’s Copa America after they were invited to play in the coveted South American tournament.
The Socceroos could come up against the likes of Brazil, Argentina and old rivals Uruguay in the competition in 2020, which will be co-hosted by Colombia and Argentina.
Milligan believes the experience for the national team will be priceless.
“To be exposed the team we have, and the young players coming through, is invaluable,” he said.
“It’s not very often you get invited to a tournament like that. We will grab it with both hands and it will be a great experience for everyone.
“We have expectations on things like major tournaments and competing with the world’s best teams, there’s no other better place to prepare for that than playing there.”
