Re: More Magic than Goldilocks orbit distance...
"Earth has a one in a million combination of life supporting conditions."
It could be a billion trillion to one, but the number of planets out there is still much greater than that. It is almost certain that, somewhere around the universe, there are thousands if not millions of planets that have magnetosphere with liquid iron core, rocky surface, liquid water, oxygen atmosphere, large moon and approximate earth size, density, orbit and spin.
The real problem is that the very vast number of planets that make this almost certain makes it extremely unlikely that we can ever find these planets. It's looking for a needle in a million haystacks. Of course if we relax the requirements a bit from 'quasi-earth' to 'just about habitable', there could be many planets that we manage to find fitting the bill. Even then, we simply do not have the capability to get anywhere near any of these planets. Currently we don't even have a theoretical way of interstellar travel in a human lifetime.
So, not wanting to be overly pessimistic, of course it's important to discover as much as we can about alternative boltholes. But for the moment, space colonies with artificial gravity or caves and tunnels dug on the moon, andgetting resources from asteroids and other moons, seems to be the best next step.