Well I live in TX and do a lot of contract engineering work for all the utilities in the state. TX is somewhat unique as we are not directly connected (AC) to the national grid. Our interconnects with AR, LA, NM, and OK are all DC interconnects. In addition we are exporters of electricity as we have more capacity right now than we use.
However we are not that much different with respect to PIEV's as not only will capacity be an issue, but the big issue will be distribution. Capacity is fairly easy to solve, build nuclear plants. The expensive and most time consuming problem is completely upgrading the transmission and distribution infrastructure.
The good news if EV's become mainstream there is plenty of time to build the network out as it will take 20 to 40 years for the EV to take hold and replace ICE for light vehicle transportation fleet in the USA.