Satellite navigation has been used for aircraft navigation for more than 50 years. In the last ten years, the capabilities of satellite navigation have been expanded to more demanding phases of flight, in particular vertical guidance down to 200 ft, thanks to the implementation of augmentation systems. In this paper, we attempt to predict the state of satellite navigation in the next 15 years. We will start by reviewing the challenges that must be addressed by satellite navigation for aircraft guidance. Then, we will describe the current techniques that enable satellite navigation for aviation and the level of performance they achieve today. This will be followed by a description of the upcoming changes to satellite navigation, which include the launch of new constellations and the introduction of new civil signals. Despite these developments, satellite navigation is inherently vulnerable to radio-frequency interference so that backup navigation systems are still necessary. Nonetheless, these improvements will have a great impact on the availability and level of service achieved by satellite navigation, in particular enabling worldwide coverage of vertical guidance.