The big bash is a comp that appeals more to ultra casual cricket fans that are looking for a socially acceptable night out with family / date and want some 'atmosphere'. It has minimal appeal to bona fide cricket fans and as a result will have almost no longevity, because people will move onto the next restaurant/activity/event that comes along leaving very few people behind. While it still averages higher than Super Rugby teams I wouldn't be surprised to hear that it's done and dusted in 5-10 years altogether.
I say this because our society is highly trendy and being in vogue is everything. As soon as the big bash starts to produce some dire atmospheres and it all gets a bit low energy jeb they'll get into a deathroll, the bad press from whoever the rival media org to the host broadcaster is will eat them alive and all the casual fans will be off doing other =things.
A great question to ask about the big bash is can you name the team who won it last year? No one can. I don't know who's won it ever, and I can't be bothered looking it up to write this comment. That shows that no one actually cares about who wins the competition, it's just an entertainment device for people looking to do something.
If anything though, this should give us rugby fans hope - there's a huge casual sporting audience out there that will tune straight back in as soon as we're a big event with lots of people talking about us (Rugby World Cup 2027)