Even the low-drawing games at Optus get more people than the WACA's capacity.There is not going to be a reduction in the number of games being played due to TV rights/advertising dollars. What I would do is have each teams home games split between their main home ground in the City (4 games) & regional/smaller venues (3 games) As an example:
Adelaide Strikers 4 games Adelaide Oval, 1 game Glenelg, 1 game Whyalla, 1 game Port Lincoln
Brisbane Heat 4 games Gabba, 2 games GC, 1 game Cairns
Melbourne Stars 4 games at MCG, 3 games in the East - 1 game Junction Oval, 1 game Casey Fields, 1 game Traralgon
Melbourne Renegades 4 games at Marvel, 3 games in the West - 2 games at Geelong, 1 in Ballarat
Sydney Sixers 4 games SCG, 3 games along the Coast such as Newcastle, Coffs Harbour
Sydney Thunder 3 games Giants Stadium, 3 games Canberra, 1 game Blacktown
Hobart Hurricanes 4 games Hobart, 3 games Launceston
Perth Scorchers 4 games at Perth Stadium, 2 games at WACA, 1 game Mandurah
Ideally the games in Capital Cities would be played one a week over four consecutive weekends Fri/Sat/Sun so fans know there is a game each weekend to attend. The regional/smaller venue games early to midweek.
The irony of this proposal is that Cricket Australia did away with State based teams (which is still my main preference) which under this proposal BBL teams return to de-facto State teams garnering support state wide.
And Mandurah? Laughable.