I blame the businesses. I've been watching. Wrigley's, the gum maker, and Miller Brewing in particular have been guilty of catering (sucking up, actually) to the illegals with all-Spanish billboards and posters in the Houston Heights and other "barrio" areas. Banks put up posters in their lobbies, using the "mirroring" technique, and that tells you who they think their customer base is -- 75% of the images are of minorities, and the only Caucasians have white hair and dentures. The grocery stores are stocking pure-Mexican foodstuffs: prickly-pear leaves, varieties of Mexican peppers, made-in-Mexico soft drinks, tortillas, tamales, chorizo and cheeses with labels all in Spanish, Spanish signs all over the store, staffs that are mostly illegals who speak very little English (don't bother asking a stockboy for anything), young employees with gang tattoos, and in the case of one Mexican-oriented grocery chain (their store colors are the national colors of Mexico), nighttime ads on indie TV in Spanish, touting foodstuffs "que nuestra giente prefiere", an ad so incredibly ethnocentrist that if an American chain ran the English translation for "foods that white Americans prefer", they'd be instantly bashed coast-to-coast by the PC Media mandarins for racism.
In addition, check-cashing businesses sprouting everywhere with prominent signs advertising cheap money wires to Mexican corresponding banks. Even the stores in the nearby malls don't stock the same merchandise -- the same selection and quality -- that the suburban stores in the same chains carry. I didn't know that last, but the women on our civic club's executive committee filled me in, in a hurry, when I inquired about it in the course of a discussion of the quality of businesses in our area possibly affecting property values and ethnic turnover ("white flight"). What happens is that businessmen spot a demographic trend and "consign" whole areas to the "future barrio" category and act accordingly -- and in so doing, work mightily to create the changes that otherwise we have attributed, in ignorance, to the "invisible hand of the market". There are no invisible hands in the market -- only visible people. And businesspeople have an awful lot to say about the changes you are pointing to, IMHO, and have in fact caused a lot of them, themselves.
I have a Travelers Express Moneygram poster that I picked up in a check-cashing storefront business last year. The poster is 100% in Spanish and features heavily nationalist, ethnocentrist, and I think Aztlanist themes in a section of mural that is the main image in the ad. The slogan is De Paisano a Paisano, which is overtly nationalist or possibly ethnocentrist. The largest image in the ad is of an Indian warrior wearing a jaguar helmet and claws, a breastplate (as for war), and a large Virgin of Guadelupe, an ethnic emblem, on his shoulder. The warrior-figure, in scale gigantic, is kneeling with his arm around what looks like a conjunto band. Elsewhere in the poster, a woman with her family approaches a cash register bearing the de paisano et cetera slogan, and she is wearing a broad sash with a map of the New World on it -- which certainly looks like an ethnic territorial claim to everything from Alaska to Patagonia. It might be interesting to see the whole mural, but the poster is a decoupage job, with bits integrated and repeated here and there. The title at the top is Los Tigres del Norte, which I suppose is the name of the band, El Norte meaning variously the United States, or in Mexican usage sometimes the industrial belt of northern Mexico, which has acquired a regional distinction among Mexicans.
The point here is that this poster was a promotion by an American business wanting to do business with Mexican nationals in the United States: Envio Internacional de Dinero was the business at hand, as defined by the poster. In so doing, they elevate nationalist Mexican and ethnocentrist mestizo and nativist themes at a time when willingness to assimilate, as you pointed out above, is cratering. This is highly significant, and businesses are part of the problem here.
If someone else has seen this mural and understands its symbolism, I'd appreciate a post-up.