It will do just fine depending on the opinion of what's considered successful
Probably something that doesn't get discussed enough.
There are different ways it can be deemed successful, and different objectives.
It obviously needs to be financially sustainable and of course lots of people would only consider Big Bashesque commercial growth as the only KPI. But you could also make a case for the women's league increasing the AFL's positive engagement with girls and women, which should in turn benefit the men's league (memberships, ratings, mums being more agreeable to their sons playing footy instead of soccer).
You can also look at public health outcomes like increased physical activity in adolescent girls and young women (big public health priority at the moment) as an indicator.
That's not even getting into the more social/cultural airy fairy objectives like self esteem for girls and women, diversity and inclusiveness, etc.
You're right that the league won't compete with prime time men's sports but I reckon it will be successful in a lot of ways.
There was also a lot for WC to gain by having a team and I'm pretty annoyed we didn't get the licence. Could have completed the ten year PR/cultural change and the timing couldn't have been better with Freo's mini meltdown over the off season