With the wide spread of autonomous relationship new identities, sexual orientation, etc. it is not surprising for people to think so optimistically about decline and even the abandonment of marriage.
Of course, with this sort of common sense, I believe I could defeat a debate against those who promote gay marriage...such as...why even bother a 'marriage' for the gays?
As for this group, well, their own irresponsibility in a true communal relationship will reveal itself through its fake mask in time. I could either tackle it now or wait for it to explode itself. It is not my priority right now.