Why is it a given that the ALP wont support the libs?
Not in Labor's interests to do so.
In fact, it could be argued that forming a minority government (even if they could) is not in Labor's interests (re: next election). Bowen said on Q&A it was an error last time under Gillard in hindsight.
Better for the ALP to play a patient game and the old school Australian political card of promoting a stable united single party that can govern in its own right versus a messy, divided and unstable (greater) coalition of non-Labor parties. Economic uncertainties and deficits aren't going away between now and the next election, and neither is more years of a Turnbull (small l)/Abbott (conservative) divide within the LNP, and nor is this even more difficult and eclectic Senate.
More of what we've seen from this LNP government will have the electorate bringing their baseball bats to the next election and the ALP will only need to pick up a further handful of seats to gain majority government.