While I understand what your saying at some stage in the next decade or so boomers will be a minority and if they see an advantage in demonising them to win over a younger demographic to gain votes imo they willThey'll never demonise the rich. They're still a party of the rich at their core. They just demonise to win over stupid people.
The reality that many on the fringes overloop (UAP and Greens alike) is that most people are actually in the centre, so it makes sense that the ALP and LNP are very similar. Any time one party drifts too far to the fringe, as the LNP have done now, the ALP move more to the centre, capture that vote and win the election.
Now, if your'e on the fringe, sure it looks like they're just the same. But the reality is that almost everyone who lives in the cities of Australia are pretty much in very similar financial positions. The main outliers being those very well off who vote LNP for their own financial benefit.
This is generalised/simplistic left-right spectrum, but it plays out over and over again and the media fuel the fire and maintain it.