A lot of
stats at pollytics shows pretty clearly what you probably suspected -- the in Australia the conservative Coalition parties gets a lot of their support from people that are from older generations. Specifically, their support is much higher among over-60s, who make up over a quarter of the population.
To put it bluntly, this means it is likely that Coalition support will fall 0.5% every 5 years for the next couple of decades as their supporters die. Given that they are currently in a losing position, it means that climbing out of that electoral hole is going to be pretty hard. When you add migrants (who trend very much towards the ALP), it gets worse for them.
There are also signs that the ALP has a similar big generational lead among much younger generations. Generally, there is a pretty good chance that unless the Coalition is able to drastically improve its appeal to younger voters soon, it is pretty much doomed to spend most of its time in opposition for a long while. The Coalition, I have to add, shows no signs of improving its appeal to younger voters whatsoever.