Unfortunately, our culture (all of our media) poisons and subverts the traditional values of immigrant families within a generation or two, almost without fail.
The "they are natural conservatives" fallacy is demonstrably BS. Name one "natural conservative" immigrant group that votes their supposed beliefs.
Once implanted in Sodom and Gomorrah they say "when in Sodom and Gomorrah, do as Sodom and Gomorrah".
Leftism (all of our media) is akin to entropy and chaos. Death and destruction.
It subverts and inverts true morality.
They aren't conservatives (at least not the way that is used in American Politics) which is one of the reasons they vote Democrat in such numbers.
But I've spent a fair amount of time in Central America, and working closely with immigrants (1st, 2nd, and 3rd Gen) from that area. They aren't the hold hands and feel the love liberals white American Liberals assume they will be. Not by a long shot.
In many ways this conversation is a mark of the American conceit. These new immigrants aren't liberals or conservatives in the American Political sense. Why would they be? They aren't from this culture, and their basic assumptions are different. I haven't personally seen the one and two generation huge shift you talk of, but we are in very different parts of the country.
I think if the current crop of democrats succeed in bring this huge, unlikely to assimilate, population into the Democratic party, they will find themselves voted off their little island. What the American Left will be at that point will be.....hard to predict. Probably even more socialist and/or full on communist.