Originally Posted by SaltyDog

Yes, we need the USAF to project airpower (including space airpower)
Yes, We need the Army to wage war on land and occupy
Yes, We need the Navy for our seapower projection (Maritime strategy)
Yes, we need the USMC to be able to project our power ashore from a Maritime delivery mode. (and to give the Army an example of a real 'soldier' <g>)
Yes, we need a Coast Guard to maintain/protect the navigable waters domestically and coastal law enforcement.
We need them all, we need to work together, and we are like never before.
The overlaps are necessary. Each service needs a certain amount of organic capability) Marines/Squadrons aboard ships for effective power projection.
USAF has/does coordinate between all services (in cooperation) with other services.
If we dilute any of the services essential missions, we will become even more costly. I hope we don't blend like Canada.

1Seat1Engine: Why does the USMC need their own airpower? Because all services need a certain amount of organic capability. Reason Navy turns F-18's into tankers at the boat. Like USAF has some of their own oceangoing vessells/tugs etc. The Navy doesn't need to run those organic requirements. If they did, they would always be at USAF locations anyway and someone would say cheaper if they were USAF. Thus, they are.
We can mass forces, yet do our independent missions as needed by national policy, we need certain overlap to ensure mission success and cost savings.