Lifespan

Other than Apple, nobody here can provide a definitive answer as to how long any device will receive support - and the Terms of Use that govern participation within these Support Communities disallows direct speculation.

That said, update support for devices will usually continue for as long as the device’s hardware is itself able to support an updated version of its OS and continue to provide adequate performance. When update support is eventually lost, hardware/repair support will continue for a number of years thereafter. Again, looking at model history, iPad will typically receive update support for four to six years from initial release.

History shows that it is usually system resources (such as RAM and CPU requirements) that ultimately determine end-of-life for OS support. The current minimum RAM requirement for iOS/iPadOS15.x is 2GB; the iPad Air4, released October 2020, has 4GB RAM with an Apple A14 CPU.

Support by App developers for older device models are invariably linked to the OS version that the developers continue to support - as many Apps are reliant upon API and system-calls provided by the installed OS. Typically, major developers will support the current and two/three previous major OS versions - some supporting even older versions.

While it is impossible to provide a definitive answer, I hope this insight proves to be helpful.

At the very minimum, 5-years for Apple support and 2-3 more years of third party app support, thereafter, for a total of 7-8 yeras of complete device support.

Currently, the 2014 iPad Air 2 will be supported, by Apple, for nearly 8 years!

Once support ends from Apple for these 7-8 year old devices, third party app support will continue for another 2-3 years more, thereafter, making a total of 10-11 years of complete device support.