My take: If marriage really were dead, people would not respond so powerfully to the idea that marriage matters because children need their mom and dad.
If you despair, I respect that, but why try to get others who have hope to despair? Do the things for which you have hope. But you may be wrong about the future. Do not discourage others who have hope from acting on it.
My other reaction: Our “traditional” view of marriage was won by the Church over several hundred years of argument with pagan philosophers. What we did once, we can do again.
Your time-frame is short-sighted.