Nate Silver has a very interesting post , with funky charts, illustrating the fact that many of the demographic designations we use to parse elections don't work nearly was well as people think.
I think he overstates one point however. He notes that Hispanics care about many issues other than immigration, and that's true and means that neither party has a 100 percent hold on the group. For example, Hispanics are less pro-choice than most Democrats and more pro-social justice than most Republicans. But, when one party is hellbent on deporting you or your cousins, it seems to me Hispanics will see that issue in existential terms, not in terms of one policy preference over another. And, once an issue is seen as extistential, well, it burns deeply into one's attitudes and those attitudes can keep going for more than a generation.