Australia will need to remain closed for decades

And if it does look like it will remain closed for that long, expect to see the Australian population decline as migrant families leave permanently. Living in Australia should not mean living in exile.

The article is an exaggeration. Once most of the people is vaccinated and the pandemic is over, it will be safe to open again.

Perhaps with some intermediate steps, like requiring vaccination certificates, of even some quarantine for arrivals. But this was already used for other illness like malaria, so it's not new or unimaginable.