I believe with the mexican immigration we have a unique situation as to assimilation. In the past no one ethnic or national group had sufficient population numbers to tilt the native established culture. Now with the established population and increasing numbers coming in from Mexico with a common language the Hispanic Mexican immigrants can trump the native culture and langauge by the sheer number of people with a common background . They may follow the European model where in many European nations you have clusters of non native speakers often due to war or earlier migrations going back hundreds of years such as Germans in Poland, Hungary and czeck Republic. It's a new ballgame.