Say what you will about the 'struggling' Lions, but they're sustainable and not going anywhere anytime soon.
It's more likely than not that a larger percentage of Brisbanites born now will follow the AFL over NRL than in past generations as a mere fact of it being an accessible option, and those numbers will continue to increase with each future generation until they reach market saturation. There's also very little that the NRL, or RL in general, can do to directly impact that outside of work in the grassroots and waiting for them to make mistakes and capitalising on it.
BTW, the 'struggling' Lions had more members than the Broncos last year, have a solid average attendance depending on results, and they made a profit in 2021, so I'm not really sure how we're defining 'struggling' at this point. Is it just because they get a larger grant from the AFL than the Broncos do from the NRL?
A larger grant that the AFL sees as a long term investment into growing their fanbase in Brisbane/Queensland BTW, and which has worked so far as Aussie Rules is bigger now in Brisbane/SEQ than it's ever been, and has a steady growth rate.