With the exception of a handful of airframes produced by the Japanese and Russians it doesn't appear than any serious work has gone into flying boats since the 1950s. With the demise of our MPAs, SAR and no carrier borne AEW / tankers I wonder whether it is an idea that could eventually be revised. Granted we have two big floating decks on the horizon but other than the possible exception of the V22 nothing that could provide tanking, COD or high altitude AEW. Never mind long endurance ASW or SAR. Apparently those pesky Iranians have revised the idea and deployed a squadron of stealthy ( I'm guessing this means plywood) small flying boats.