As someone said, before WW2 there were few long runways and flying boats seemed to be the future. But once all those long wartime runways were built. The poor economics of flying boats alongside landplanes became obvious.
Dornier still have a flying boat:
When I win the Eurolotto I might buy one!
But really I'd love a Catalina. There's a crashed and dismantled one sitting at an airport here. I had a good look over it. I reckon it's restorable. Another plan for the lotto win.
There are plans for a seaplane service to and from the town I live in. So far it's only a website, aspirations and some proving flights in Cessna 172 floatplane. But I have my resume in with them. I'd fancy seeing out my career flying seaplanes.