Well Speaking as a Texan I do not think we are turning purple or blue. Obama performed better here in 2008 than in 2012. Abbott will outperform Perry and Cruz is wildly popular. Other than what the MSM or Dems say, I see zero evidence of TX becoming anything but more red.
Your observation is correct. There's no evidence whatsoever that Texas is moving left. In fact, it's been moving rightward over the last ten years. Electoral results bear that out.