Curious does raise some good points, I mean lets be realistic, everything isn't all rosy in Queensland, and to say the Lions going through a poor patch will help change that is a tad short sighted.
Anyone over 15 is unlikely to change from primarily been a League fan to an AFL fan or vice versa, but those under the age are at an influential point. The Lions and AFL have done a great job in promoting themselves to schools and so on, and whilst the Broncos and NRL were a bit slow, they are beginging to catch up slowly but surely.
Another NRL team in South East Queensland will hurt the Lions a lot but will do a huge amount for Queensland. First off it brings back the whole Local Derby style game Brisbane has missed since the Chargers and Crushers have been gone. This is a huge crowd puller as shown by some of these past crowds for matches:
Broncos V Sea Gulls - 57,212
Broncos V Crushers - 49,607
Crushers V Broncos - 34,263
There is no reason those types of crowds can't be pulled (well okay there is for the first one cause Lang Park isn't that big) if a Gold Coast side exists.
So yeah you now have 2 games a year which will have all of Sth East Queensland will focus on. Throw in the possibility if both faced each other in a final? That would be a sellout and a half.
