Fatigue damage is one of the major design drivers for structural components of wind turbines. These machines are required to operate continuously over a lifetime of more than 20 years, during which the fatigue damage progression is influenced by control-induced loads and site-specific environmental conditions. Loads can be influenced in various ways through the wind turbine controller, e.g., by derating the power or by operating in partial overload. Since fatigue progresses slowly over the lifetime, each component or even failure mode has an individual fatigue budget that can be utilized optimally. To obtain the maximum long-term benefit from each individual fatigue budget, the trade-off between energy production and load-induced damage needs to be balanced over the complete life cycle. For each failure mode, we can compute an optimal long-term operational planning that allows for optimal distribution of the damage contribution over the entire or remaining lifetime. This is conducted using deterministic assumptions about wind conditions. Now, we use uncertainties of annual wind distribution parameters as the basis for a probabilistic assessment of the lifetime of each component. This allows for combination using a reliability model, which yields the lifetime of the entire wind turbine system. The impact of individual component optimizations on overall system reliability is evaluated. Results show that all approaches yield a potential for extended lifetime, however the margin and the secondary impact differ greatly. Simultaneously, the span of probabilistic lifetimes emphasizes that uncertainty has a significant impact on the selection of an optimal strategy. Our findings provide a step towards a probabilistic and reliability-based long-term operational planning for an entire wind turbine system that is composed of multiple components.