In highschool we were taught of “party realignment” to new voter preferences, where it seems in parliamentary systems they would just form new parties and let the old ones die off. (See the UK now)
It’s not entirely due to the republican structure of government, because the US did cycle through a few parties before landing on these two. Republicans being deified for winning the Civil War makes sense but why did the Democrats not die out at least?
Counterpoint: Australia has a deeply entrenched two party system and they have preferential voting so getting rid of FPTP is no magic bullet and you should be skeptical of anyone who tells you otherwise.
That being said, it seems like Australian politics is in flux and it’s likely that it’s heading into a period that could be a more pluralistic party system but it’s also likely that one party will displace one of the Big Two and the system will continue on largely unaffected.