I think I follow what you are saying, but I'd disagree with one thing: For consumers, all these devices come from the same company, and are developed with (broadly) the same process. Because these products are related, a consumer can make assumptions about both new and old devices. In fact, there is evidence that they do, if you take a look at secondary markets for Apple devices.

What you are saying is similar to telling a consumer that they should not trust Toyota vehicles to last longer than any other brand. When, in fact, there is a general trend that Toyotas do last longer. Sure, you aren't guaranteed that one specific Toyota Corolla will last longer than another specific Ford Focus, but there is a general trend you can rely on.