Would certainly be an interesting election to see for sure. I could easily see a Hillary/Rubio matchup resulting in a bump in the number of whites voting Democrat and Hispanics voting Republican.
How so? Because of white women? Certainly possible.
White women, and the view that Obama's 39% among white voters (especially in a victory) was an aberration. Similarly, his high performance among Hispanic voters was another aberration. I don't think Hispanics are going to become a monolithic Democratic voting block like some seem to believe, nor do I believe whites are going to be a monolithic Republican voting block.