Not trying to shoot down your idea, but there is absolutely
nothing that flying boats can do now that current aircraft cannot
do better already in the arenas.
ASW and patrol were the two main jobs of the Sunderland
and catalina. We don't have subs and just about any aircraft
including bombers is faster and can spot a battlegroup just as
easily.
While they do have uses in scenarios, both would be sitting
ducks.