Sailboat sails seem to last 2.5 years. I’d think most of the low hangig fruit has been picked here, and that a kite could not easily last longer.
If we have an automated deployment machinery for the kite(s) we might also assume that only half the time is windy enough for production, furter extending that. In northern and southern parts of the world, the windiest periods coincide with less amount of sunlight (winter), another factor to extend lifetime in practice.
For me it seems simpler to keep it flying year round than implementing such deployment machinery. Both are very hard though.