- Kessler Syndrome, a la "Is the plotline of Gravity inevitable with increasing commercialization of space?"
- Weaponization of space. If you could get 4 unauthorized satellites up on a launch that was forbidden because "they're a danger to other satellites", could you do the same with satellites that are intentionally a danger to other satellites? Could a private company knock out the U.S's spy satellites at just the moment they are most needed? Could it set up its own spy network?
- How about ABM defense? Could a private company create a network of smart space junk with the purpose of stopping a potential nuclear war before it starts? (Incidentally, such an organization could end up in the position of both saving humanity and opposing U.S. national interests, given that the U.S. has the largest stockpile of nuclear weapons on Earth, which should make Americans wonder if U.S. national interests are aligned with humanity. Crimson Tide was a great movie.)
- More generally: nation states have traditionally had a monopoly around certain technologies. Spaceflight, weaponry, cryptography, communication networks. That monopoly is fraying, or in some cases, has already frayed beyond repair. What does that mean for the power balance on earth, and for social organization on the planet? There are some private organizations that are arguably more powerful than full nation-states nowadays.
21st century sorts of problems indeed. At least the 21st century looks like it'll be exciting, if somewhat scary.