The British and Irish Lions fly-half sat out Saturday's 40-9 Samoa victory with a hip problem, but is expected to be ready for this coming weekend's visit from the Wallabies.
New boss Schmidt was boosted by Ulster outside-half Paddy Jackson's confident turn at the helm as Ireland racked up five tries at the Aviva Stadium.
But he also conceded Racing Metro star Sexton will be the front-runner to start against Australia in round two of the autumn internationals.
Schmidt explained: "Obviously the coaches will get together and will make a decision.
"One great thing about Jonny is he's well known to me, he's well known to (assistant coach) Les (Kiss), and Plum (forwards coach John Plumtree) doesn't care because he's not a forward!
"We would have to strongly consider Jonny coming back in. He does bring that experience and that quality that we know he has.
"He wasn't the starting Lions out-half for no reason. But I'd have to take my hat off to Paddy Jackson.
"I think that he's had to do it pretty tough at times, being thrown in as a very young man and having to direct some very impressive men around the park.
"I think he said during the week about telling Paul O'Connell where he needs to be and feeling a little bit intimidated himself. I feel the same intimidation."
If Sexton is the clear first-choice fly-half, Schmidt admitted the battle for the understudy role remains fierce.
Ulster's frontline 10 Jackson led the Ireland line with assurance while Ian Madigan might have got the nod for the North American summer tour, but has had to bide his time for chances behind New Zealander Jimmy Gopperth at Leinster this term.
Schmidt admitted provincial opportunities certainly sway the thinking at national level.
He continued: "I just feel that Ian Madigan hasn't had too many opportunities this year, but he came on and you immediately saw a little bit of spark.
"He wasn't at 10 but his versatility allowed us to rest Drico (Brian O'Driscoll) a bit and get him on there.
"I think at 10 we are building a little bit of depth and I hope that continues to grow and part of that growth is having a competitive environment.
"I'm not great at projecting things, but I know next week that we're probably in a better place than if Jonny played this week and we needed to replace him through injury.
"Every game is a final for me at the moment, and of course you always put your best team out in a final, every time.
"At the same time you're trying to grow a group, so I'm relying on the provincial coaches to continue to give opportunities to guys at Pro12 and then particularly at Heineken level."
Ireland's autumn series is building towards a showdown with New Zealand.
But Schmidt admitted he cannot let himself look too closely at the All Blacks' impressive 26-19 victory over France - not with Australia descending on Dublin next.
He added: "Australia are the third-ranked team in the world; we're a fair way off that.
"I can honestly say New Zealand are not really in our mind.
"I know who they are. I know they are coming on November 24.
"It's tempting I admit to start looking at them, but we've got to be Australia-focused."
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- Paddy Jackson