"if it were left to the forces of Darwinism alone..."
"... rebelling against the otherwise universally selfish Darwinian impulse".
Altruism and concern for the future of the planet are products of Darwinism alone and we're not rebelling against the selfish Darwinian impulse. Dr. Dawkins cites the use of condoms as another example of Homo Sapiens rising above Darwinian self interest. I don't think so. Care for the future of the planet and deliberately acting in a way that will limit the spread of our DNA are not contrary to the "aims" of evolution.
Our brains are set up to feel sexual urges. Even if we don't want kids we still like sex. We act on the sexual urges not just on the desire to have kids.
Dr. Dawkins' YouTube video "Nice Guys Finish First" is an interesting look at the subject of altruism. Playing nice with others is a good stable survival strategy if others are doing the same, so it feels good. Playing nice with future "others" feels good too, even if it doesn't benefit us in any other way.
Sex with no offspring feels good. Being nice with no chance of reciprocation feels good too. We haven't broken contract with Darwinism, we've just found loopholes.