Judging by skeuomorphic icons that got stuck in the past, they usually get stuck with the last iteration of tech that is single-purpose and unambiguous.

For example, the icon for "train" is most often a steam train, even though they haven't been common for a very long time. But there's nothing else that looks like a steam train, while a diesel/electric train just looks like a generic box when on a small, low-resolution icon.

The disk icon for saving got stuck because it's the last piece of storage tech with a clearly recognizable shape. SD cards are just rectangles, hard drives or SSDs also don't really have a clearly recognizable shape (especially not to someone who has never taking a PC apart).

But the floppy disk icon won against e.g. drum storage (which is sometimes still used as an icon for databases) or tape storage, because it was newer and more widely used.

The landline phone icon wasn't replaced by a smartphone, because the smartphone isn't single-use. It's ambiguous what e.g. an app with a smartphone icon would do, since a smartphone can be used for a ton of different things.

So in short, an icon gets stuck with the

• newest tech
• that is single-use
• that has a clearly recognizable shape

From then it stops mattering whether the tech depicted is still in use or even known by the youngest generation. It's now not the "floppy disk icon" but the "save icon" instead.

I think up until which point you would still call things like that skeuomorphic is entirely subjective, depends on how you want to define it. These things will always be of skeuomorphic origin, at least.

It's a very interesting process indeed. I imagine these designs will morph over time into something else, as their original meaning does not matter anymore since no one remembers it vividly, and all that matters is them being widely known and distinctly recognizable. Just like it happens with words changing over time.

I’ve frequently wondered what the phone icon will be when the current meaning is lost in time. Will it be an icon of the device you’re using? That doesn’t make sense. Maybe a person talking? Not sure.