I recall reading a remark to the effect that "by the time we reach the stars we won't need planets". The author was making an argument that the problem of building a long-term-viable artificial habitat in space is vastly easier than and probably a prerequisite for interstellar travel, so that building living-space for humans is easier and more cost-effective than interstellar migration.
I want to quote the remark in one of the articles on the website describing my SF RPG setting, but I can't remember who wrote it, and my efforts with Google aren't availing. Can anyone help?
I´m not sure if he used those exact words, but Isaac Asimov makes that point in "Extraterrestrial Civilizations".