"Indeed, Texas has the potential to become a leading exporter of electricity to other states if, and when, the United States completes a national power grid.." That will never happen. There are a few direct lines between the Texas grid and the other grids, and they are very controlled, and easily disconnected. At this point in time, Texans probably would sooner secede from the Union rather than tie their power system to a national power grid. It seems to me one time, they did in fact try to connect the grids and a group of Texans cut the lines.
By remaining isolated from the national grids, Texas escapes being subject to FERC regulations, so it's not likely that anyone will want to change that. However, since Texas has a surplus of power, neighboring states might be screaming for access to that power if there is a national shortage.
That will make for some interesting politics.