This Sports Illustrated article is interesting: How Private Golf Clubs Are Still Legally Able to Discriminate Against Women, SI Golf July 1, 2019
So, this article is not directly about saving women's sports but I do think it's relevant for this Circle. It reviews legal grounds for private golf clubs to exclude women, which in turn may be useful in considering ways that women's sports organizations might be able to exclude men.
According to the article, civil rights laws allow private groups to engage in sex-based discrimination for freedom of "expressive association".
If associative expression is legally protected basis to discriminate based on sex, then women should be able to discriminate on that basis in private organizations, such as private sports leagues and clubs or private schools. That approach may not solve the problem for public schools but could it be a place to start?