iOS 11 will render older iPhones, iPads and apps obsolete (And potentially cause issues with 32-bit apps in compatible 64-bit devices).
Apple’s iOS 11 update means iPhone 5 and 5C will no longer receive updates because they are 32-bit devices. Even on compatible 64-bit devices that started with the iPhone 5S and iPad Air in 2013, some 32-bit apps and games will be incompatible after switch to 64-bit.
Users can check which apps and games are affected by navigating to:
Settings > General > About > Applications > App Compatibility
This is analogous to the upgrade from Windows XP (32-bit) to Windows Vista / 7 (64-bit) that caused problems initially with some 32-bit software and applications. Most incompatibilities were eventually addressed by the software manufacturers to fix them and make them compatible with the new 64-bit Operating System releases. For some, it was trial and error, most eventually got everything working correctly, while some never could get things working 100%. Years later, there were some developers and some older software that didn't invest the time and resources to upgrade their software to make them fully compatible with 64-bit architecture. The possibility of the same scenario exists with iOS 11 as well.
The new iOS 11 will be available as a free update for supported iPhones and iPads in the summer.