Texas is massive, bigger than many countries and bigger than several nearby states put together. Most forms of geographic and other kinds of risk could be smoothed over with sheer scale. We have massive energy production resources including not just oil and natural gas, but way more than our fair share of nuclear, wind, and solar. Most likely we'd be helping other states much more often than they help us. The TX grid is a mess due to sheer mismanagement and poor regulation, not so much being disconnected from our neighbors. It's maddening how little it would take to do better, like just better weatherizing the nuke plants and the gas pipes feeding natural gas generation so it doesn't go down when there's a worse than average freeze.

A US wide grid failure can’t cascade into Texas if Texas is not connected. Most national grids have plans to run areaa in island mode in case of catastrophic failure, but who knows how well that would work.