But, but an agreement will not help this situation. The customer will say that "my system used to work satisfactorily, now it does not. It's broken, fix it." Unfortunately, this will not be possible.

Apple is forcing developers to update their Apps or be de-listed from the App Store. I've also seen some nag messages when attempting to update non conforming App's. Some of the new features are not supported on older iDevices that can't run the latest versions of iOS.

In this case one could instruct all customers to refrain from updating their Sonos system and control Apps, but this is not a permanent solution because adding a new Sonos component will force an update as part of the process. Further, if a visiting relative updates Grandma's Sonos App in an attempt to help out, Grandma will be facing a new, unfamiliar UI.

Another example of an App that is somewhat broken is FING, a popular network analyzer. The current version of iOS will not return the MAC Address of a network client, previous iOS versions would report this. As a result, FING does not work as well as it had, because it cannot report MAC Addresses.