The SeaPlane as an assault platform? As a Special Ops insertion platform? For long range at sea rescue? It'll never happen but the R3Y Tradewind makes you wonder about possible applications in our era.
Side Note: This is one of those concepts put forward by Mike Sparks and the pics are from his website, Combat Reform. He hates the Marine Corps the way that I hate Amos but he has some interesting ideas and even if you disagree he has some informative info. Quite honestly its also one of the major sites on the web for large parts of little known military history. You should get over your bias and check it out. But be warned. His pages will kill dial up connections...high speed internet only.
Side Note 1: I keep coming back to this concept because it so fascinates. A P-3 aircrew that has to land or God forbid bail out in the open ocean is going to be in serious trouble. Outside of the CH-47, CH-53 or the V-22, we just don't have the aircraft that can reach far enough. Besides the V-22 I don't know of any that can get there FAST enough. The Japanese and Chinese both operate Seaplanes in the Rescue role. Considering the Pacific battlespace perhaps we should consider it too.