Really...........
No mobile, personal device maker supports their devices forever.
You will find that Apple supports their mobile, personal devices longer than any other device maker.
You are being unrealistic in your expectations.
Your iPad Air 2 may get iPadOS 14 as this will be, largely, a code optimising/code fixing/debugging OS version with very little in the way of new features.
So, your already nearly 6-year old iPad will get one more year of iPadOS upgrades/updates, but eventually ALL support for your iPad will completely end.
This is already happening for anyone who owns 8 and 9-year old iPads in 2020.
Both Apple and just about ALL popular third party app developers have permanently removed, for good, ALL older iOS compatible versions of their apps from Apple's iOS App Store servers.
These older iOS version apps are all permanently gone forever from Apple's iOS App Store.
So, it is just a matter of time for all other iPads made after 2012 through 2014, or so.
So, full end of support for these 2013-2015 devices is coming.