"Separate but equal" as to race was declared unconstitutional in 1954. However, SCOTUS has still not taken the additional step of legislating sexual behavior to the same protected status as race. The Lawrence decision comes close. SCOTUS' next Euro-progressive pro-sodomy decision may do just that.
Will all-gay public schools be thereby found unconstitutional and dissolved? Don't count on it. This SCOTUS has shown a consistent and predictable inclination to make up rules as it goes to advance the personal biases of its liberal majority. This SCOTUS believes "gay is okay and les is best," so it is likely to do everthing it can to encourage such "affirmative" segregation (as long as gay students are getting specialized, high-priced faclities and assistance).