The US military will not be left behind in the shift from a few big satellites to thousands of more effective smaller satellites.
SpaceX's president and CEO (Gwynn Shotwell) says SpaceX would consider launching weapons into orbit for the U.S. government, if asked.
The US military (Undersecretary Michael Griffin) has talked about spending $20 billion for a network of a thousand hypersonic missile interceptors. $20 billion is just the low ball bait. Even if an initial system went up for that price or less, they will rapidly increase the scope and scale.
DARPA is developing the basic technology for a lot more small space satellites.