Their prior behavior leads me to believe eventually their OS refuses to be compatible with their older hardware. When the user plugs in their hardware all of their apps demand updates. The apps then update automatically and then refuse to work with the older OS.
The user is then forced to dig through their cache to find older versions of their apps and keep them in a secure place in case iTunes decides to update them again later. Eventually this battle against updates becomes worth the cost of the new device.
Forced obsolescence by software, it's worked well for them in the past, no reason to see why it's not going to keep working in the future.