The concept of a WGU state subsidiary is not new or unique to Texas. In fact, WGU Indiana
is already up and running, and WGU Washington
is being set up. WGU Texas will be the third.
I think the idea is that a "WGU State" school can be specifically tailored to meet the academic/professional requirements of a particular state. As a totally hypothetical example, suppose you take accounting classes online through WGU Indiana. In this case, there might be a guarantee that the credits will transfer into B&M programs at Indiana state universities and community colleges, and there might be a guarantee that they will meet the licensing requirements of the Indiana CPA Board. The same sort of thing could apply to teacher education, as you suggested.
You might not have such assurances with generic WGU classes; WGU obviously enrolls students from numerous states, and so their programs cannot be tailored towards any one state in particular. In contrast, WGU Indiana only admits Indiana residents, so they are free to develop customized WGU programs specifically to satisfy the existing Indiana educational/political establishment.