I sort of disagree, since the real military function of flying boats is to suppliment naval assets. As Mark indicated, helicopters based on ASW ships, coast guard ships, and CV's can handle all of the search and rescure and military functions of flying boats. Regarding possiblly greater vulnerability of airfields to cruise and ballistic missiles, this could also impact the other role of flying boats as long range transports. I presume they need to
"land" at fairly developed port facilities with rail and road connections to efficiently off-load equipment, supplies, and men. Couldn't these facilities be attacked by missles just as effectively as airfields?
Maybe you were hinting at this, but your idea of not developing SAC as well as the whole separate Air Force (something the Navy was all against anyway) is a thought. Maybe this could lead to situation where the Navy becomes the USA's only long-range nuclear deterrent arm, based on an essentially mobile and difficult-to-strike triad of (1) CVN taskforces, (2) ballistic missile subs, and (3) long-range turbojet or turboprop flying boat strategic bombers operating from and and constantly shifting among many small "bases" - essentially surface tender ships - anchored at atolls, islands, and fjiords throughout the Pacific and cosatal North America, Scandinavia, the Med, and elsewhere?