I do find it interesting that Hispanic majority communities along the border (such as Laredo, RGV, and El Paso) all have successfull country stations.
Have you been to the Houston Rodeo? There is a ton of 2nd generation (and up) Hispanics attending the country acts. I know that this observation is anecdotal evidence, but country music seems to be more popular with
newer Hispanics than most people would think/guess (well, at least in Texas. I won't speak for places like California or Arizona).
A few months ago, someone sent me this cover of Garth Brooks' "Friends in low places"
LINK (YOUTUBE). Sure, this is definitely more "indie" than mainstream, but it goes to show you that the appeal for country music is there for newer generations of Hispanics. This assimilation (and blend) is not reserved for just 5th or 6th generational Hispanics.