De Nosotros

A few days ago, on a major street I saw an advertisement in Spanish for a national bank.
It said:
No de nosotros (Not ours)
This shows the partial dissappearance I have witnessed in Spanish, particularly in the Americas, of the possessive pronoun nuestro for the locution de nosotros, literally translating to "of us", meaning somewhat "belonging to us". For instance, instead of Esta es nuestra casa (This is our house), one would hear Esta es la casa de nosotros (lit. This is the house of us, i.e. that belongs to us). It happens generally colloquially, with the written language, as well as the formal one, using indeed the proper form of nuestro. We find the four forms of the third-person possessive pronoun being displaced by a one phrase:

Singular
nuestro (m.)
de nosotros
nuestra (f.)
Plural
nuestros (m.)
nuestras (f.)

Ordinarily, de nosotros is used as a stressed, emphatic form of the possessive, i.e. Esto es de nosotros (This belongs to us [and not anyone else]). This is similar to what happens with vosotros, which can assume the same use in Spain, i.e. Era de vosotros (It was yours[pl.]), which can also be Era vuestro. However, the use to which I'm referring replaces even the untressed forms. The rest of the possessives are used as one would expect: Es tuyo (It's yours), one would generally not hear Es de ti; Es mio (It's mine), not Es de mí. The third person forms are a bit trickier since there can be ambiguity, i.e. Es suyo can truly mean "It's yours (sg., polite address)", "It's his/hers", "It's yours (pl.)", or "It's theirs". This ambiguity is solved by using the stressed pronouns themselves, in the same construction as de nosotros: de usted (yours [sg.]), de él (his), de ella (hers), de ellos/ellas (Theirs), de ustedes (Yours [pl.]). So that we hear: el gato de ellos (Their cat), la casa de ella (Her house). Usually, though, the proper form the third person possesive, su, is preferred, with the de + pronoun used mostly when the context might be ambiguous, for instance, when talking about his and her house, where the forms for "his" and "hers" are the same; or, for emphasis (i.e. it's his car, not hers). Certainly, the third-person stressed forms with de are not used nearly as often as they are in Brazilian Portuguese, where the disappearance of the second person forms (tu, vós) from the pronominal system, forces the almost imperative use of de + pronoun, since seu (suyo in Portuguese) has become generalized with the meaning of "yours (sg.)". The written language does use the third person possessive with reference to the other persons (yours [sg.], his/hers, theirs, yours [pl.])., but in the spoken language these are displaced by:

seu(s), sua(s) (yours [sg.])
seu(s), sua(s)
seu(s), sua(s) (his)
dele
seu(s), sua(s) (hers)
dela
seu(s), sua(s) (theirs [m.])
deles
seu(s), sua(s) (theirs [f.])
delas
seu(s), sua(s) (yours [pl.])
de vocês

These stop agreeing with the subject to agree with the possessor (except with vocês, which is gender unvariable), as it happens in English, and the four possible forms merge into one. So that we find: É a sua casa (It's his house), agreement is made in sua with casa which is feminine singular. However, what we would generally hear is: É a casa dele, with agreement in dele with the possessor, masculine singular. Or, São os seus carros, with the meaning of "Those are her cars", seus agrees with carros, masculine plural. Again, what we would hear is: São os carros dela, now the agreement being made with the possessor, ela (Her).
The forms with de are the ones used ordinarily to emphasize or clarify the context, as in Spanish. They are used as well in Portugal under those circumstances. In Brazil, we can fairly say that the seu forms, other than to reference você, in the spoken language have disappeared. So, instead of Isto é seu in Brazil, with the meaning "This is theirs [m.]", we would hear Isto é deles because, as I said, for Brazilians, seu is felt to implicitly mean "yours [sg.]". There is indeed a difference in the frequency we find the forms with de in Spanish and in Brazilian Portuguese. The replacement of all the grammatical third person forms with de + pronoun in Brazil could be compared to the replacement of de nosotros in Spanish. In that, both uses are very similar. The usual unstressed forms, without de, are indeed kept in the formal language, and, in some speakers in general. In Portugal, the second person plural, vós, has disappeared as well, just like in Brazil, both now using vocês, which is semantically second-person, though grammatically it uses third-person verb forms. The possessive for this in Brazil, as I say above, is seu in the written language, and de vocês in the spoken one. In Portugal, however, there is an asymmetrical use of the second-person plural possessive, vosso, belonging to the now archaic vós, employed with the third-person pronoun vocês. In Brazil, we sometimes find this as well in the singular, where teu (2nd person) may be used with você (3rd person). I shall discuss this asymmetry in depth in the near future.

I should say that de nosotros is not ungrammatical, it is just as correct as its unstressed form nuestro, even though in writing, the latter is preferred.
We would then hear:
-¿Dónde está la casa de nosotros? for the more usual ¿Dónde está nuestra casa?
-Este es el de nosotros for Este es el nuestro
-Or, as I read in the ad: Problemas de nosotros for Problemas nuestros