Massive first preference vote losses maybe, but the preference flows would still trickle down to two major parties, it always does.
That preference flow data can then be used to shape future legislation to keep voters on their side and even to pull swing voters from the other sides, or at least that’s how it is supposed to work when the media isn’t actively working against you.
“hey we only won because of votes from this minor single issue party, maybe we should consider our position on that issue”