Recent Harvard Law graduate Katherine Kraschel's Note in the Harvard Journal of Law and Gender argues that women's colleges need not worry that admitting transgender students would compromise their ability to remain single-sex. She explains:
Title IX provides for affirmative action not only for women, but also for the non-advantaged gender, and transgender individuals are most certainly members of a disadvantaged gender. Title IX case law, such as Miles and the cases that follow, shows that despite the dichotomous conception of gender when it was enacted in the 1970s, Title IX can embrace the notion of discrimination not only against the non-advantaged gender, but against the non-advantaged genders. While this is not well-settled law, if women's colleges strive to “be at the forefront of [transgender equality], not sort of catching up to the rest of the world,” the logical step is to end reliance upon Title IX and embrace an inclusive conception of Title IX's anti-discriminatory charge.
For more, see Katherine Kraschel, Trans-Cending Space in Women's Only Spaces: Title IX Cannot Be the Basis for Exclusion, 35 Harv. J. L. & Gender 463, 483 (2012)