I think it makes a lot more sense to build our own garden ships than to try and find/terraform/colonize a distant world. There's no need to travel
at ridiculous speeds if generations live on the ship, and have an ability to sustain the population.
Artificial insemination and beaker-babies, aboard a space-fairing biosphere, could well be the future of our species if we're forced into space by a
disaster here on earth.
But the time to think of these questions is NOW, not later, not 'when it happens'. The more prep the better our chances of survival.
One way or another this rock is going bye-bye, eventually. Whether the sun eats us, or the core cools, or the humans do something stupid - it's
going to happen. Best to plan for sooner, rather than later, and get a move on.
I really like the idea of farming in space, especially if the water comes from fuel cells. It wouldn't be practical to cart up enough water for
several generations, but there are options. Ice-farming might be another one of them.
I agree that we're intimately connected to this planet, but I don't think the prospect of life in space is so impossible. Technologically speaking
it's quite a lot easier to engineer, compared to sustaining life under the oceans, isn't it? Much easier to build for a vacumm, at least in terms
of ensuring structural integrity, and the consequences of faliure are no less-drastic underwater.
I envision humanity in the future as a loose collective of self-sustaining, self-governing colonies cast out in all directions. It would also be a
chance for practically limitless sociological experimentation, to see what works and what doesn't - we could refine and improve our social structure
until we find a form of education/government that adequately suits our needs.
I've never been one to keep all my eggs in one basket, no matter how large and lush and beautiful the basket happens to be. I love earth, but I
think it would be a mistake to cling to it when we have other options. Just as every child leaves home, so must we.
Unless you want the future of humanity to resemble some 40 year old living in his parent's basement, subsisting off of porno and pop tarts.