I recently heard an anecdote that involved a teenager seeing a rotary telephone and not knowing what it was. Similarly, there's a funny scene in the movie In and Out in which a supermodel runs afoul of a rotary phone. In both cases, the idea was that although rotary telephones still exist, they've been largely supplanted by the push-button variety.
So when you talk about calling someone using a push-button telephone, what verb do you use to describe the act of pushing the buttons? Most people casually use the term "dial"—even though there's no dial involved. It seems likely to me that in the future people will wonder (and some probably do already) why the word "dial" is used to refer to the act of pushing buttons on a telephone.
I use the term "obsolescism" to denote a common word or phrase that's currently in the process of losing its literal referent. Plenty of words have, over time, come to mean something other than what they originally referred to; sometimes this is because the original referent becomes obsolete, sometimes because the word starts to be used metaphorically. Such words may have been obsolescisms in the past, but most of them are not still in the transitional period between old usage and new.
Obsolescisms ought to be easy to find; they should occur, for instance, in referring to cases where an interface to an underlying technology is changing, while the underlying technology (or some form of it) remains in place. The telephone being the perfect example. Unfortunately I've had a hard time finding others.
Some people still say "mimeo" or "mimeograph" when referring to making photocopies; and I'm sure there are still a few scattered mimeograph machines in use. But this usage has become very rare. Part of the definition of an obsolescism is that the term continues in wide use after its referent is gone.
Most "type foundries" these days create typefaces electronically rather than by melting metal; but perhaps that usage is more metaphorical than obsolete.
I gather that quite a few people still refer to accounting as "bookkeeping," even in cases where the "books" are kept with accounting software on a computer. Similarly I suspect (though I don't know for sure) that suspects are "booked" at many police stations by having their names entered into a computer, rather than into a physical book. Likewise with a company "booking an order."
I suspect that "wearing a wire," carrying a hidden recording or broadcasting device, originally referred to wire recordings (which I'm told preceded magnetic audio tape). But "wire" here may just be synecdoche, referring to the wires that are part of the device. Most likely "wired for sound" and "wiretap" refer to wires used to carry sound-as-electrical-impulses rather than wires used for magnetic recording. But the "wire services" used to send their news via telegraph, and no longer do, so that counts.
My dictionary implies that "monitor" referring to a computer screen derives from a similar screen used to monitor a camera signal; alternatively, "computer monitor" might refer to using a screen to monitor the internal state of the computer. Either way, the term is an obsolescism. But the term is going out of favor; recent usage tends to prefer "display" over "monitor."
"Two bits" is a term that was once an obscolescism. I wonder if in the future people will think the term "two-bit" (meaning cheap) was derived from computer systems, in which two bits isn't much memory, rather than from money that could be broken into eight bits.
Finally, another possible future obsolescism: it seems unlikely that the World Wide Web will ever entirely supersede print as a medium, but if it does, people may occasionally wonder why the basic unit of Web content is called a "page."