While the largest group immigrating into the US are Mexicans, we can see here that people from other parts of the world are immigrating. The non-India, non-China, non-Cuba immigrants may be somewhat surprising. The key here is that no one group really dominates the immigration picture. Sure, Sam Huntington's dead body would still point out that Mexicans are number one, but the new Americans are a diverse lot.
This is good for a number of reasons, but my point here is that it means that there is less of a sense by those already here that they are being swamped by one group with one set of values (as if any one group entirely shares the same set of values). Sure, I got a strange Mexican-ization question earlier this year about the forthcoming US Civil War II, but the reality is there is probably less antagonism and less strife when the newcomers are a mix. Which values will alter the existing American ones? Those based on Hinduism? Catholicism? Buddhism? The answer is none of the above.
Instead, my guess (as a non-expert on migration) is that the American stew will just have a few more spices, but will remain largely the same. Sure, there will be more non-whites compared to the whites, but more brown Americans is only a probably if you are ... racist. Sure, parties that pander to racists might suffer, but there is an answer to that--don't pander to racists. For all of Stephen Harper's problems, his brand of conservatives long ago figured out that playing to immigrant communities was good for their political chances. Democracy is kind of cool that way--if you want more votes, then appeal to those beyond your narrow group (if the lines and institutions are drawn the right way).
Anyhow, the real contrast is between the US and its European friends who are facing heaps of stress with their immigrant populations in part because of the relative size of the flows, in part because they are relatively new to the immigration game, and in part because the immigrants all seem to be part of one community.
One joy of the Furth of July is that the ideas behind the declaration, once one corrects for gender, apply so broadly--that all people are created equal, with rights to life, liberty and happiness (property sounds so crass). The American struggle is not with the ideals but how to implement them well. Because if we don't have cool rules ourselves, we will be bogus too, as the great political philosopher Jeff Spicoli instructed one score and twelve years ago.