If a 2nd Perth franchise starts up, I bet you it won't be the worst franchise going around. I'm certain it will perform better off the court than 2 current NBL teams - Townsville and Wollongong. Even if they play at Challenge Stadium, which would be logical, they could still get a decent following.
However, it won't happen. Without going into the commercial issues that would face a 2nd team there are other factors preventing this (which is unfortunate, as Im sure everybody wants to see more NBL teams).
Even if there was a bid to get one started (has there ever been interest in a 2nd Perth team?) they would be completely overshadowed by the Wildcats profile. If you live in WA and like basketball, chances are you're a Wildcats fan. And if you're not, then you're not into the NBL, so don't bother.
From a media perspective, they wouldn't survive. Even the Cats - with their 11,000 crowd average and strong brand presence in Perth - battle to get on the sports news on a regular basis. Can you imagine a fledgling expansion team?
Besides, at worst, rather than creating new fans, you will most likely be taking away existing Wildcats fans that may want to follow a "battler/ underdog type" team. Can't see many people wanting to do that anyway.
It won't happen. Unfortunately.