Colin Gray has a short article on security situation in the 21st century that I just read. It suggests the future will be characterized by the following:
- Great power rivalry
- Adverse climate change
- Resource rivalries and shortages (food, water and energy)
- Disease pandemics
- Jihadi terrorism and insurgencies
- Nuclear proliferation
- The "unknown unknowns" (the things to worry about if we know about them, for example, asteroids)...
- "global economic meltdown"
That about sums it up!