If Smith isn't there, they still got Labuschagne who got 50+ runs. He may not be as good as Smith in building partnerships but still he performed well so Aus too have a chance but still rain has a better chance. :-P
It is raining quite heavily in West Yorkshire (where the Leeds cricket ground is located), but the weather predictions are saying that things will get better after Thursday. So although the first day of the play may get disrupted by rain, the chances are that the next four days will be free of any such disruption. Remember how close was England to a win (the injury suffered by Smith played a large role though), despite almost 150 overs were lost to rain during the Lords test.
That said, Steve Smith has attracted criticism from medical circles, after he chose to resume his innings despite the head injury. Check this:
https://www.bbc.com/sport/cricket/49395198It was "incredibly dangerous" for Steve Smith to resume his innings in the second Ashes Test at Lord's, brain injury charity Headway has claimed. Smith was hit in the neck by a 92mph bouncer from Jofra Archer on day three but passed an initial concussion test and returned to continue his innings. With concussion, the vision can be blurred and the brain can be slow at processing information. That leads to delayed reaction times and is just incredibly dangerous.
I don't want to comment on this, but I thought that without Smith resuming his innings, Australia could have lost the match. He added some valuable runs and prevented England from leveling the series 1-1.