Postecoglou's side defeated Honduras 3-1 in the second leg of their inter-continental play-off in Sydney to secure their place in Russia next year.
But the 52-year-old's future - despite reaching the finals - is far from clear.
Postecoglou has come in for regular criticism over the course of the qualifying campaign, which saw Australia finish third behind Japan and Saudi Arabia in their third-round group, before scraping through a play-off against Syria to set up the clash with Honduras.
There had been talk that he was planning to stand down after Wednesday's clash in Sydney, regardless of the result, and the former Brisbane Roar and Melbourne Victory boss offered no assurances post-match, saying: "I'll sit down with the powers-that-be over the next few days and we'll discuss everything, bring it to a head and make a decision."
Postecoglou, who said that his family had "endured a lot", continued: "If people still think that I go around worrying about what other people are saying, trying to get some vindication, they've missed the last 20 years... I've been coaching for 20 years, mate.
"I won my first championship when I was 31 years old and, you know what? I could coach for another 20 years and I'll always be an outsider in Australian football.
"I don't have the glittering Socceroo career that you need.
"But that's fine. I wear that as a badge of honour.
"The more that comes my way, the more determined and resilient I am to just keep going down my own path.
"It's worked well for me. Some people don't like it.
"To be fair I've had a hell of a lot of support from players, coaches and just the general sporting public.
"There's not a day goes by where - maybe I just see the nice ones - people are consistently giving me encouragement and that's all I need.
"The people who don't get me have never got me and will never get me."