Well, I'm reading the original note and it says that 5 resolutions are needed to fully change the law on Oaxaca. They have 3, if 2 more cases are approved in Oaxaca the law is going to change.
It doesn't changes the law automatically in all of Mexico. But it's a precedent in which if someone demands their own state, they are surely going to win. So, this almost opens the door for same-sex marriages all around the country.