With all the capacity shortage issues at big airports and all the arguments for new runways etc with politicians, residents and green campaigners getting in the way and nothing getting or done or taking years to do anything why not switch to something more radical?

For somewhere in the UK, Heathrow and Gatwick with their endless capacity issues could move many of their flights to Brighton and a large seaplane airport could be built where planes could just take off from the sea. It a great idea IMO.
Of course normal airports and normal planes would be kept but every sea or riverside town or city could have its own seaplane airport which would require no runway resurfacing etc, would be cheaper to run and would not require tarmac for runways.

Of course it will never happen but its fun to speculate.

For example if I wanted to fly from St Louis to New York I could fly on a seaplane from Mississippi River over to the coast of Long Island or to the hudson.
Most of JFK's flights could take off and land from sea of Long Island's coast and most of LGA's flights could move to the hudson river.