The women's leagues in the US is a hard question.Here's an off-topic tangent for you: the NWSL. Reading this, I had the thought that the NWSL and the MLS should essentially "merge", and MLS teams should also be fielding women's teams, much like the Premier League teams do. More revenue for the MLS stadiums, and hopefully a better deal and better exposure in better markets for female professional soccer players.
There are groups interested in setting up women's teams here, CFG and Barcelona for example, because it could be a large market.
But at the same time the attendance and tv ratings aren't there to justify a large scale investment.
Any league like that will have to be built like MLS. It's going to take committed owners with deep pockets who aren't afraid of taking a loss for the first few years.