If humanity ever truly leaves the Solar System, do we eventually settle another planetary surface, or do we become permanently bound to interstellar space and build our own worlds instead?
Assume that, at some point, humans become capable of physically leaving the Solar System. Not probes, but actual long-duration human civilization. Would we really still think of the spacecraft as transportation? Or does the spacecraft itself form the basis of our new world?
If a population spends hundreds or thousands of years aboard a self-sustaining worldship, that ship would become the environment people are adapted to physically, culturally, socially, and probably eventually biologically. It would have its own gravity, atmosphere, ecology, agriculture, day/night cycle, infrastructure, and built environment.
The question that I am grappling with: Do we expect the descendants of the original travelers to abandon the world their civilization has spent centuries optimizing so they can adapt themselves to some planet with different gravity, radiation, atmospheric chemistry, seasons, biology, and day length?
Or would the more likely model be that they remain a spacefaring civilization? In this scenario, star systems are not necessarily a place to alight. They are sources of energy, materials, scientific opportunity, and perhaps new locations to position additional artificial habitats.