The architecture of the future will be less inspiring than what we see in science fiction. One of the consequences of more energy efficient design will be more practical looking buildings, devoid of the sculptural exuberance of the past several decades. We might have a revolution in culture and values that results in more durable construction methods and longer lasting buildings, but the current trend towards disposable systems is not showing signs of slacking off. Location will continue to be the determining factor in longevity.
Before the curtain falls I think we'll have a population on the planet that will have peaked at around 12 or 15 billion people. The built environment will be distinguished by lots of abandoned settlements in unworkable areas. In fact, we can expect an end to housing shortages, even if we wreck our agricultural land.