How long can a habitiat survive?

Don't forget the learning curve in any innovation. Plus, you're making the
same mistake of assuming that decades after the first construction that
technolony and cost will remain the same. They don't stand still but are
always in movement. Take the nanotech. Already, 30 companies dealing with
nano are in talks for IPO in 3 years. So decades after first Island 3, we
can expect new nanotech and robotics to be self-organinzing healing agents
with stuff such as self-healing windows. So like I say, it get easiler over
time, like a good painting.