Exactly, I suspect there is nothing we can replace it with. A TV with rabbit ears will always be a TV - perhaps a hundred years from now?
(Disclaimer: my ability to draw is very limited so this looks unintentionally minimalist, because my "boxes" are just squares.)
You could have some convention which says, say, "the present file is a sort of ball or rounded object, the filesystem is a box where we can put our balls, the clipboard is some sort of stack of stuff," and so forth. Phones could look more like mobiles do now, if you put them in a bit of perspective and gave them a keypad. Rather than using the page for a generic document, we have the ball for that purpose, so we use the page instead to indicate printing, since you're converting the ball into a piece of paper.
I think wrenches, magnifying glasses, and binoculars can stay as iconic things -- but since people now use magnifying glasses for "zoom" we should perhaps stabilize on binoculars for "search"/"find". (And come on, I'm not Sherlock Holmes. I'm not trying to find a clue, I'm trying to find last night's homework.)
Email is much trickier; if we don't keep using envelopes, I don't know how we would iconify that.
What's the most iconic image of search? Finding a needle in a haystack. Well, that won't do. Second most iconic image of search? Police searching a home. Looking for your keys. Rummaging couch cushions for change. Steal the Google logo.
Some ideas of search are okay, but don't play well with the other icons -- a piece of paper with text, one of the lines suddenly jumps to a fragment of blue text. (It works if your "find" highlights a word with a blue box when it finds it.)
The closest I have come to another good icon for search is to try to denote the question, "where is it?" This could be a question mark with the "box" which represents the filesystem. Perhaps many balls are shown coming out of the box. Or perhaps a stack of notecards with one of them being pulled out.
"Call" is different because I have too few ideas. A phone, perhaps. Two faces seen in profile could mean "converse" with the implication that there will be voice. Or an ear, perhaps, with its oblong shape. Telephone wires are iconic in parts of the US, but are an oddity abroad. And beyond that, I'm a bit lost.
The irony here is that he has no problem calling the device he uses a "computer", despite the older definition no longer holding true, or especially referring to "files", which is certainly not a term used in the old sense.
Dijkstra's "On the Cruelty of Really Teaching Computer Science" rails against analogies (the source of these terms) at length, but I'm not certain that there's much validity to the argument when the new meaning of the term eclipses the old one.
It would be a little like living in the Firefly universe but with more iPhones.
Now, if we had all the icons in all apps replaced consistently with Chinese simplified characters—that would be fun. I don't think it would be such a disaster (except to icon design business profits), after we rediscover how functions map to pictures again we'll continue to utilize UIs as usual. Admittedly a bit slower because of more complex hanzi shape, but without having to deal with badly designed or inconsistently used icons[0].
And also we'll be sure that when a new concept appears we will have an icon for that. If not—well, we'll start combining hanzi.
[0] An example of one such goof: http://plus.google.com/photos/108564542236590882918/albums/p...