The AFL acts against this by centralising revenues and actively designing a fixture that favours larger clubs over smaller ones in the Melboure space. On the one hand the AFL wants them to get out of their own mess, and on the other it actively prevents them from doing so.
You mention Fitzroy which hit Tasmania, Canberra and Carrara before it was fashionable, and had a big offer from the ACT that the AFL knocked back. These days - and given this was before the AFL started sending the Swans, Dogs, Demons, Saints and North there - it was a bit rich. Nowdays a deal like that would be taken with reciprocal memberships in Melbourne and the works. (i mean besides the obvious GWS complication)
I was a touch out on the number of times they make the cutoff.
SkyNZ averages were 60k for the year, including Origin, Finals and Nines. Only round 25 v Gold Coast hit 200k, with most matches falling between 70 and 140k. Game against NTh Queensland in Round 3 only hit 30k, Canberra 38k, Souths 40k, Brisbane 42k, Penrith 41k.
Ratings are all listed here as published on Throng.co.nz - http://www.footyindustry.com/?page_id=209
West Coast membership numbers have been passed in recent years by collingwood, Essendon, Richmond and are being caught by the Adelaide clubs.