Death of a pronoun
In classical grammar, words are divided into two groups: content words and function words.
Content words include nouns, adjectives, and adverbs. They "paint a picture" of what's going on in the sentence, and new content words easily enter the language. (Think about all of the new words for technology that didn't even exist five years ago.)
Function words includes prepositions, pronouns, articles, and conjunctions. They aren't as visually evocative (with the arguable exception of prepositions), and their number is fixed. (I.e., they don't enter or leave the language.)
Of course, that's merely the classical view of grammar. Linguists point out that if function words genuinely never changed, we'd still be using Proto-Indo-European prepositions. (Hint: We aren't.) However, it is true that function words change more slowly in language, to the extent that many people don't realize they change at all.
One of the more notable losses of a function word is the disappearance of the second person singular pronoun in English. In Shakespeare's time, English speakers had "thou," "thee," "ye," and "you" to choose from. In modern English, all those forms have collapsed to "you" (with the exception of a few dialectical groups, such as Quakers, and the rather misguided attempts of some Mormon leaders). (Along those lines, why aren't Mormons concerned with reviving "ye," as well? Or "yourn"?)
In French, the first person plural pronoun is in the process of disappearing. That's right, French is losing "we" (well, nous.) Is there a deep psychological basis to this loss? Are Francophones, worldwide, narcissistic enough that they only think in terms of "me", not "us"?
Not exactly. The verb conjugation that goes with nous is somewhat difficult in French. It's longer and tends to be more irregular than the conjugations for je ("I"), tu ("you," sing.), and il/elle ("he/she"). (Although it's arguably not any harder than vous ("you," pl.).)
In contrast with English, the third person singular impersonal pronoun (on) is alive and well. (The English equivalent is "one," as in "one does what one must," but it sounds much more stilted in English than in French.) Also, on is easy to conjugate because it follows the same pattern as il/elle, so on is actually starting to replace nous in spoken French.
Here's an example: When I went to the French department office to pick up a parking pass for our group on Monday (btw, I'm in Québec for the week at an intensive French program), I said "On revient," which literally means "one comes back," but which was understood as "we'll come back." I could have said "we will come back" ("nous revenons"), but that's a whole extra syllable and I was tired after the drive from Quebec City, you know?
Sometimes people also say something like "nous, on pense que . . ." which means "we, one thinks that . . ." and makes the reference clearer, while still avoiding having to conjugate the verb.
Of course, French students are still going to learn to conjugate "nous" for many years to come, and language "purists" will probably bemoan its disappearance as a sign of the decline of civilization or something. In the meantime, if you hear a "nous" verb in the wild, take note, because they're becoming rare.