Very similar to the west coast-fremantle argument in 1995
Eagles were successful and hugely popular, although some people still hated them. If you asked them people at the time they would of said they'd prefer to cheer on their favourite Melbourne team. The dockers initial fan base consisted of people who preferred Melbourne clubs, and west australians who initially still supported The Eagles. Over time that fan base grew, people ditched their Melbourne clubs for a local team that wasn't the Eagles. The people who still supported the Eagles and the dockers started to favour the dockers because they were the underdogs, these people eventually stopped supporting the Eagles all together. Now days the Eagles and Dockers have 2 huge but completely different fan bases that hate each other , and are both success stories in the afl (despite fremantle winning no premierships in that time).
Brisbane is a huge city, 2 million people plus the other heavily populated areas of SE QLD, it is a rugby league mad territory, and the population is only going to grow. If in 10-15 years we still only have 1 team in the city and 3 overall in Queensland then the nrl is failing