Except not really, West Coast and Fremantle have a brand new stadium and still haven't had a single sell out, comparatively Origin in Perth for next year has already sold out.
GWS cracked 25,000 members this year and their crowd average dropped from 13,000 to 11,000. Gold Coast Suns membership has decreased to 11,500 when three years ago they were bordering on 14,000. Their attendance looks to be about 11,000 average.
The Brisbane Lions crowds and member numbers have dwindled significantly over the past decade, currently at 20,000 members from a franchise high of 30,000 in 2004 and average attendance of 16,000.
The only non-heartland team making inroads is the Swans and they've had decades of leg ups from the AFL to establish them. They existed in a single product market for 30+ years with no direct competitor. I have no idea how valid claims that a lot of mid-90s Bears fans became Swans fans, but former ARU boss John O'Neil was in the Herald last week saying he gave up on Union and started following AFL along with a bunch of other Waratahs/Union diehards who gave up over how shit the Wallabies are and started following the fumble game.
AFL membership numbers aren't all ticketed members. it's just the amount of emails sponsors have access too which is attractive to corporates.
and yes, I'd say much of the swans support has drifted over from union. it's not like the NRL has done anything to get the north shore onto rugby league's side, both with a team and a decent venue to play out of. but it's an extra 30-40k each fortnight that could have been attending an NRL match, and they have the money to do so.