While as some have said, this is probably just political theatre and they'll renegotiate an agreement before the next federal election. It does however pose some interesting points depending on who broke off.

You've got the nats breaking the coalition possibly feeling emboldened by the most recent results. However I can't see how they really gain any seats outside electorates they already hold seats for.

I think it's far more interesting if you look at it from the libs breaking the coalition. You now have the libs free from far right policy agreements that they would have passed in a coalition so you could see the libs in the senate being able to help vote more centre labor policies. Might shift power away from the greens in the senate.

Definitely an interesting development and not something I would have expected as an outcome from the election!