I think there will be a crisis or catastrophic event that will take our attention away from terror or war and as a positive response may redefine our focus of the century.
A global pandemic/epidemic - the positive response: New found respect for natural systems and focus on health.
Environmental tip. A phase change with a irreversible climate change - the positive response: Understanding balance with natural systems.
Over self-consumption like the oil supply - the positive response: Might help wastefulness and make it a century of efficiency.