A few people have made the point in this thread that state vs state t20s had low crowds compared to the first few years of franchise t20s. This is true but you have to take context into account. The state Big Bash was growing in popularity and momentum every season until the format changed. The reason CA changed the format in the first place was not because state vs state t20s were unpopular, but so an extra two sides could be squeezed in so that more games could be sold for broadcast rights. At the time the local derbies in the A-League were must see events, and CA also wanted a slice of that intra-city tribalism.The people that want to go back to tradition and revert to state sides only have themselves to blame, state sides haven't got crowds or interest for years now. I occasionally got watch a day of Shield cricket and some days there'd be lucky to be 200 people there, same with the T20s before the franchises come in and the ODD comp, bugger all interest.
What really catapulted the comp into mainstream popularity was Channel 10 broadcasting it in its entirety on FTA TV for the first time. I realise it's pointless dealing in hypotheticals like this, but I have no doubt this would have eventuated anyway if the state comp stuck around. The format would likely have more staying power as well, as it is not relying solely on just being a convenient cheap night out to get bums on seats in the way the current comp does.