"...... trouble is that many/most want to live in cities and megacities..."
Personally I reckon that is a bloody good thing.
Often I fly into Sydney - sydney seems to be a good example.
What I see is that we fly over miles and miles and miles of bush/ocean and then all of a sudden we find a large city full of houses, buildings, people and everything that comes with it.
Strange - outside of this the world seems to go on quite happily.
I can just imaging some future catastrophe that wipes out the whole lot and then it just overgrows and returns to bush - hiding concrete and some deeply buried bones. Meanwhile life in the bush outside of that just goes on - oblivious.
Personally I think we think we are far more significant than we are.
