Port Adelaide went with a neutral brand and until very recently distanced themselves from the Magpies brand as much as possible, and what PR said of Freemantle is also true.It think it is fair to say that it has worked for the AFL with Fremantle and Port Adelaide. Each club has captured about one third of their city as second to market. Neither club is in the centre of town but now has fans right across town. No two (or three) situations are the same but it can work.
In other words, no it hasn't worked for the AFL as the AFL has never attempted what the Dolphins are attempting.