If anything, the more rural, poorer, and older Dixiecrats were the last group of Southern whites to switch to the GOP-not just at the Presidential level, but the state and local levels too.
To this day there are Democrats running unopposed in rural Texas.
http://www.texastribune.org/2010/10/08/rural-white-democrats-in-republican-sights/After the Civil War and Reconstruction Republicans were HATED in the South. Being a Democrat is just a strong tradition down there. But anyone that denies what happened after the signing of the Civil Rights act is deluding themselves. That put a lot of southern Democrats in a tough position. Some stayed Democrats and changed their views and a bunch of others slowly but surely threw in the towel and headed over to the Republicans so they could enjoy the dog whistle politics.
I think a lot of simplistic statements are made and accepted by people who have not spent much time in the South. Anyone who is honest and spent some time down there knows the deal.