So you're basically committing yourself to the position that, by allowing same-gender couples to be marry, opposite-gender couples will suddenly lose the capacity to procreate. To borrow the language of the
Ninth Circuit decision, I'm am aware of not basis on which this argument would be even conceivable plausible.
No, same-gender marriage will not stop heterosexual couples from procreating. Hell, it won't even stop same-gender couples from procreating, as they occasionally do in previously heterosexual relationships or medical intervention.
The "species suicide" belief is a bizarre fantasy which exists only in the heads of conspiracy nutjobs and bigots. It so far divorced from reality, so removed from any string of logic, so void of any factual basis whatsoever that it cannot be taken seriously any context, let alone form the basis for depriving gay couples of their fundamental right to marry.
0 for 9, getting pretty bleak now...