"I'm contracted to September 2019 and that will see me out," he told the BBC.
England finished at 180 for nine off 88.1 overs as Australia won by an innings and 123 runs.
All four of Australia's front-line bowlers finished with 20 or more wickets each for the series.
Usman Khawaja plundered a big century as Australia roasted England's bowlers on Saturday to open up a 133-run lead with two days to play
At the close, Smith was on 44 with Khawaja reaching his highest score of the series on 91 in Australia's 193 for two
Skipper Root again missed out on an elusive first century in the series as Aussies struck late on the opening day of last Test
Root and Malan stole the highlights on the opening day of the SCG Test
Woakes has taken 10 wickets at 49.5 in the four Tests and scored just 114 runs through seven innings batting number eight at an average of 16.28.
Left-armer Starc is the leading wicket-taker in the series with 19 despite only playing three Tests
Faf du Plessis, Ali Khan among replacements named for PSL 2021
Miller's explosive 85* in vain as all-round Pakistan take series 2-1
India's spinners thrash England to win second Test by 317 runs
Court of Arbitration for Sports reduces ban on Umar Akmal from 18 to 12 months
David Miller set to miss first half of PSL to take part in domestic competition
Mohammad Rizwan to lead Multan Sultans in PSL 2021
Motera stadium in Ahmedabad renamed after Narendra Modi
PSL 2021: PCB allows 50% crowds for remaining Karachi-leg matches
Play and Win with 1st Cricingif Play League
Bonner's patient half-century keeps West Indies steady on opening day