As part of an update scheduled to land next month, Pokemon Go will drop support for a couple of popular iPhones, as well as iOS 10, 11, and Android 5.
The iPhone 5s and iPhone 6 will no longer be supported following the update, which is unfortunate but ultimately inevitable.
In an upcoming update to Pokémon GO in October, we will end support for Android 5, iOS 10, and iOS 11, as well as iPhone 5s and iPhone 6 devices. Trainers with devices not specifically listed here will not be affected and don’t need to take any action.— Pokémon GO (@PokemonGoApp) August 31, 2020
Anyone buying into Apple's ecosystem knowns that their device's long-term usability is limited. Still, the iPhone 6 only launched in late 2015 – less than a year before Pokemon Go's launch.