You cannot predict all the possible future requirements of a product, the best you can do is make a reasonable effort. In this case the vendors likely could do some kind of patch/update to support .?, but surely there are a large number of other little things that have changed or been added over the years, not just .?. So, where does that slippery slope end? How many new features, and related regression testing should be put into older devices? Does the hardware vendor have a kind of ethical responsibility to continue to update it until it just absolutely cannot be carried along any longer?

In hardware designs there are always a lot of hard trade offs made to keep the bill of materials as low as reasonably possible. As new components become available new capabilities for the devices become possible, and at some point you need to focus your primary R&D efforts on the newer stuff just for efficiency sake.

My personal experience is that very few mainstream devices are really built with some kind of planned obsolescence. Instead, devices that become unsupported and unable to get current software updates are usually just victims of the basic drivers of modern business (profit, growth, etc.). Sure there are cases where the hardware vendor WANTS devices to expire early and force users to buy new ones, but when you look at the app store revenues of Apple or Google, I don't think they're sweating hardware revenue to the point they are implementing some form of planned obsolescence. They might even prefer that older devices were more cost effective to support in order to reduce the potential for churn to the alternate platform/ecosystem.