Very true, but you can also keep around an old Android phone, or even emulate an old AOSP distribution if your really need to. Obviously this is not ideal, but

Very true, but you can also keep around an old Android phone, or even emulate an old AOSP distribution if your really need to. Obviously this is not ideal, but if you're trusting your hobby or business to an app, it is in your best interest to make sure that it doesn't poof out of existence randomly before you can upgrade.