I would guess that Latinos that are descended from more recent immigrants are going to be pretty strongly Democratic, but that will vary depending on where they live. I am sure that Latinos in Texas that will be third generation in 2020 are going to be more conservative, than those in California. In the southwest recent immigrants are almost all Mexicans and so far Mexicans are one of the most Democratic Latino voting groups. I don't really see this changing quickly. By 2020 or 2030 there should be starting to be a pretty large amount of illegal immigrant descended second generation voters, with or without some form of amnesty. This generation of voters will probably be unanimously Democratic for the most part.
What I am trying to say is that it will take 30 or 40 years for Latinos to become significantly more Republican. There are just too many recent immigrants and too much of a stigma against the Republican Party with Latinos among people born recently. Rush Limbaugh had approval ratings in the single digits among Latinos, and he is considered the face of the Republican narrowly in a gallup poll.
Another big problem for Republicans will be when the turnout of Mexican-Americans starts to increase in large amounts. I am beginning to think that this is inevitable and when this happens in large amounts it will have pretty huge effects on the Southwest. This hasn't really happened yet but when it does, the Democrats' dominance over parts of the Southwest should be assured.
I think there is hope for Republicans if they support a guest-worker program. This way, they don't reward people for breaking the law, but they help those who want to make their families life in Mexico or where ever better.
Maybe, the problem with the guest-worker program is that it will depress wages of Latinos already living in the United States, while some form of amnesty wouldn't depress wages in the same. I remember that 65% of Latinos want amnesty of some form too, so the Republicans definitley have some major problems on their hands.
The only thing I see that could possibly pass with the bulk of Republicans(and no I don't mean McCain, Graham etc) is if the Pence-Hutchinson plan were revived and combined with both Democrat Heath Shuler's SAVE Act, and another bill beefing up interior enforcement as well as enforcement on the border. This would be the only compromise that could work and get my support, Pence-Hutchinson had a path to legalization with a vague touchback requirement that could be watered down if necessary but combined with the SAVE act would mean it has real enforcement mechanisms and not the half measures promised in the past two phony compromises.