I am more interested in the influence of Spanish on South-Western accents of American English than vocabulary loans from Spanish. Do you have any information on that, from personal observations perhaps? Are non-Hispanic people from California beginning to adopt some pronunciation features from Hispanics? Do you think Spanish could have a significant influence on Am.English in the future?
Why the concern with only the Mexican accent effecting English spoken in South Western states?
There's also the Cuban accent of the South East, and the Puerto Rican accent of the North West. There are a lot of Cubans in the North East also
Then there's the whole slew of various South American Accents.