First of all, deciding how to utilize our military assets is best left to the professionals who understand the big picture. Understanding the big picture also includes planning for the future and anticipating our needs. Camp Pendleton sure seems like a big, empty area when you drive by on the 5 but appearances can be deceiving. Once you take away a base, it is gone forever.
As for increasing the size of the airport, that may not solve the problem. Airspace and air traffic patterns may be the biggest stumbling block. I haven’t studied the issue, however.