There is a large disaffected Conservative population that has yet to warm to Trump as myself. Intense state pride like nowhere else, and the strong country culture that makes the state Republican. Yea, I really don't see competitiveness.
I don't believe anyone is promoting the argument that Texas is competitive this election cycle, but it is definitely remarkable that it is potentially much closer than anyone might have thought.
Having lived in Texas for awhile, I do get the concept of "Texas Exceptionalism", but Texas is actually not really a "country state", considering that 80% of the population lives in basically six different huge Metro areas, and as an extremely fast growing state, not only do Republicans face a potential Latino problem if they don't change their attitudes (Circa California early 1990s), but additionally there are many migrants from all over the country relocating to work in the booming job markets of DFW, SA, Austin, and even to some extent Houston (Although there is always more of a boom-bust dynamic in Houston compared to other major cities in the state).
As I stated upthread, if Harris County moves from being a marginal Dem to a +10-15% margins, Fort Bend flips, and Montgomery County goes from an 80-20 Republican county to a 60-40 county, combined with similar movements in the suburbs/exurbs of DFW, then this state will start to become close.