I think there’s still enough conservative independents to protect the Libs from supply/confidence votes in parliament, even if the ALP wins the Bennelong by election.
There’s no way in hell the Libs will voluntarily call an election now, 10 points behind in the polls, and with nasty internal fights over SSM legislation and preferencing One Nation coming up. They’ll hang into minority govt for as long as they possibly can in the hope that things will miraculously improve somehow. Hell, given that 2016 was a double dissolution election, I don’t think it’s even LEGAL for them to call an election til mid next year at the earliest.
The only way there’ll be an election out of this is if the Libs lose enough MPs to 44, then lose enough of the by elections, that they lose a no-confidence vote in parliament.