Fair points. Quality dialogue, I love it.
I've never really seen it as A-League wanting to make you stop supporting another code, it's simply trying to get you across to it to spend your hard earned on it as well. It's only real rival during the Summer is Big Bash so it's not that crazy an idea to think that it won't get people through the turnstiles. It's up to them and how they do it though.
In respect of crowds that attend games like Juventus & Liverpool not translating, well they're evidence of the power behind soccer as opposed to thinking those numbers will always be at A-League games. They won't as the current model stands. However people will attend if they think they're going to see quality because we're a fickle lot and we won't watch shite. Melbourne crowds have traditionally been larger than others, particularly Victory, but they have to maintain them too. That's what the A-League has to work on. In it's favour though is that the quality of A-League games has grown substantially each year. My god, I remember the first game at Olympic Park and to see where it is now is incredible really considering the short amount of time the A-League has been around. And with that brings & keeps talent, which leads to memberships, more coin in the club coffers, etc etc etc.
Personally I'm with you in that it won't take over from AFL in the foreseeable future. What I continually see though with it is that the promotion of soccer has never had more drive or had more money than it has now. It's really up to them and how they use that from here on out.
Cheers