You'll need laws, a lot (and I mean a LOT) of education, and a lot of time. You'll need to go at least until my generation dies off before it really starts to go away, because we were raised with that binary as such a basic assumption that even for those of us -- like me -- that agree with you, it is a very difficult mental effort to even for a moment let go of the Man-Woman binary and grasp anything else. For those who cling to the simplicity of it (with some misguided and weak understanding of biology/genetics as a talisman)? You'll have to wait for them to die.