... so it is not a battle for "gay rights", but a fight against the very notion of the sexes. Gay rights are just the emotive pretext. First to go is "husband" and "wife", followed by "mother" and "father". Then it's "boy" and "girl" (these are all constructs after all). This is well under way in those polities that have passed this law.
That is why the agenda is not to abolish legal recognition of marriage and return it to the extra-legal, pre-political domain, replacing it with "civil unions". It is to turn the normative statement of marriage upon its head, de-constructing the human person in the process. This is a goal of radical feminism, and "genderless marriage" is not the endgame, it is part of the process.