What determines when a carrier aircraft becomes obsolete

How quickly would the Loire-Nieuport LN.401 and Breguet Br.810 have become obsolete?

Quickly if left unchanged, but sustained modernization could keep the design family useful for years.

The answer resists assigning a fixed obsolescence date to the Loire-Nieuport LN.401 and Breguet Br.810 concepts. Aircraft left largely unchanged can become ineffective within a few years, while continuous engine, armament, and airframe development can preserve a family much longer. The Spitfire is used as the comparison: its late marks differed greatly from the original but remained useful because investment continued. For naval aviation, the important question is therefore whether the aircraft and its carrier system receive an upgrade path, not merely when the first version enters service.