Seems like Trump did a lot better than Romney among "ethnic" whites (e.g., Italians, Eastern Euro, Catholics). Republicans already maxed out votes among white southern evangelicals... so there was no room for improvement in Texas and the panhandle.. there was room for improvement in those more ethnically diverse counties. But I think Trump maxed out the white vote both in terms of percentage and turnout. This isn't a winning long term strategy for Republicans. They seriously need to figure out how to appeal to non-white voters fast.
-Except Donald Trump improved over Romney both in rural Texas and the rural panhandle. I was kind of surprised by that myself.
Rudy Giuliani may have maxed out the White vote in the 2001 mayoral race. DJT may have maxed out the White vote in Mississippi. Other than that, there's no GOP maxing out of the White vote anywhere in the country.
Again, HRC's coalition is majority non-Hispanic White. If Trump was to pick up a random Democrat, she would most likely be White. There is as of yet zero need for Republicans to do any minority outreach at all. Rather, a posture of immigration restriction and steep taxes on out-of-wedlock births are called for.