And now we're about to lose amphibs to SOCOM.

Well not yet but this should appear to be rather ominous news to the Marine Corps.  Navy SEALs are about to take a soon to be decommissioned LSD and use it as a mother ship/sea base.  From the Washington Post.

Until December, the Navy had planned to retire the Ponce and decommission it in March after 41 years of service. Among other missions, it was deployed to the Mediterranean Sea last year in support of NATO’s air war over Libya.
Instead, the ship will be modified into what the military terms an Afloat Forward Staging Base. Kafka, the Fleet Forces command spokesman, said it would be used to support mine-clearance ships, smaller patrol ships and aircraft.
The documents posted by the Military Sealift Command in December, however, specify that the mothership will be rebuilt so that it can also serve as a docking station for several small high-speed boats and helicopters commonly used by Navy SEAL teams.

Why do I get the feeling that all the work done to make sea basing a reality was for the benefit of SOCOM...and SOCOM alone?

A lack of urgency is killing the Marine Corps right now.  For some reason those at the highest levels don't seem to understand this basic leadership trait.

You can bet  big dollars that when all is said and done, the sea base will be a victim of the Marine Corps limited budget and will only exist for the boys in Tampa and Coronado.