I think sky islands could enlarge space for populations (other than space colonization).
The problem is that one would need to somehow keep those islands in space.
Searching for anti-gravity & magnetism yielded little results.
I also had the thought of having the island having less density than air to float up, and then maintain the same density as air. It would need some type of technology that could adjust the density at the slightest change in mass or volume, however. I think this isn't very practical.
I was wondering what other (more) efficient ways there were to build sky islands, and if it would be worth the money/energy.
(Technically though, something like a spaceship may be more practical...)