Average IQ is a good measure of how well a group will do in the United States. A low IQ accurately predicts more problems in a community. Let's see where various Hispanic groups are at. To set white Americans at a mean IQ of 100, I had to set the mean IQ for all Americans at 96.5. This indicates that US IQ has dropped to a level lower than many European and East Asian countries. The results shown below are limited to Hispanics born in the US, since the measure of IQ is a vocabulary test in English, and foreigners are at a disadvantage.
White Spanish 100.3
White Cuban 99.2
White Mexican 91.5
Mexican--other race 90.5
White Puerto Rican 90.3
Black Puerto Rican 88.4
Puerto Rican--other race 84.0
The only groups with IQs similar to white Americans as a whole are people who describe themselves as White Spanish or White Cuban. We would expect these folks to assimilate well into mainstream America. Marco Rubio and Ted Cruz, for example, are white Cubans.
For the remaining groups, the average IQs are much lower, ranging from 84 for non-white Puerto Ricans to 91.5 for self-described White Mexicans. Many Hispanics consider themselves to be white which ignores the fact that most have some American Indian ancestry. As you can see, the IQ difference between white and non-white Hispanics is small. These groups are much more similar to each other than they are to non-Hispanic whites. At least in terms of IQ, it makes sense to lump white and non-white Hispanics into one group, but white Cuban Americans and those who call themselves Spanish should be lumped in with whites.
Based on average IQ, we expect these Hispanic groups with low numbers to fare poorly in the United States, and since IQ is a stable, highly heritable trait, the poor performance is likely to continue indefinitely.