I may be talking nonsense, but it seems to me that the conventional relationship, the one most of us grew up believing was the norm, is less and less popular. Obviously men and women are always going to fall in love, have kids, and commit to the long haul, but that's increasingly one of many options, rather than 'the norm'. The young seem so much more cynical and wary of relationships. I know three people in their early 30s who've never bothered at all. When I was a kid (in the 1980s) that would have been considered odd.
So, my question is (assuming I'm not talking rubbish), what do you think will replace the conventional relationship? Until very recently, women needed men. Today, women can pursue a career, own property, even have children without a male partner. As a consequence, a lot are now asking "what's the point of getting involved with a man at all? If somebody really awesome comes along, great, but if not, I'm not going to 'settle' like my grandmother did"
However, people still want the same old things. They still want love and company and security. They still want somebody there for them when they're old. And they still want sexual intimacy (as opposed to random/casual sex, which is generally unfulfilling). Do you think something new could fill the void?