"Have we asked what aircraft would ever replace the F-35B once it reaches its sell by date? The reason for this strange question is that a carrier is not a short term ship with a life span of just 10 or even twenty years."
Modern Military aircraft have a very long lifespan. The Harrier (1969) is going to be in service over fifty years as is the F-18 (1983) and other aircraft like the C-130 (1957), F-16 (1978). The Tornado (1979) should stay in service for forty years at least.
The reason why there was a high turnover of aircraft types at the start of the jet age is that the aircraft were too limited to operate effectively and caused huge death rates on carriers.