"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
Iqbal Imam appointed coach, Bismah Maroof given leadership role until T20 World Cup 2020
'We are motivated to make history by winning Test series in Australia' - Azhar Ali
‘Focusing on taking every opportunity to play for England’ – Malan targets recall in longer formats
Nicholas Pooran handed four-match suspension for ball-tampering
'Pat Cummins must get the new ball' - Brett Lee
Pakistan fans feel proud of Naseem Shah
Misbah-ul-Haq backs Yasir Shah to fire against Australia
‘Bowling out Australia A cheaply means we are here for business’ – Waqar Younis
Lahore Qalandars rope in huge names for the T10 squad
Zafar Gohar heroics keep Central Punjab firmly on top of the points table