This for discussion.
Most of the power centers of the Left are metropolises on the coasts.
Coastal cities have access to supplies that do not come from the interior of the United States.
Food can be brought into ports, even if transport on the interior is cut.
Electricity (probably limited, but much better than none) might be delivered from nuclear ships...
Maybe natural gas power generators could have have liquefied natural gas delivered via the ports.
How much control of the Navy will which side have in a CW2 as envisioned?
Most cities rely on power generated a considerable distance from the city. There are exceptions. Phoenix gets most of its power from the Palo Verde nuclear plant only 20 miles away.
What other cities in the U.S. have power sources reasonably close?
Most of Los Angeles power comes from outside the city, a good ways away.
But 33% of the power comes from natural gas plants inside the city, and 7% come form nearby hydro power plants. If LA can keep getting natural gas, they can keep 50% of their power online. They have some smaller sources that likely would add the additional 10%. Palo Verde would probably be cut off from LA. (Palo Verde supplies about 9% of LA power) The lines go right by my place in Arizona.
It may not be clear that most of the cities will be out of power in CW2.
How vulnerable the grid is for city power needs a bit more analysis. I already see substations being hardened. President Trump is taking measures to protect against EMP strikes...
Food for discussion.
What countries are going to supply food to these American coastal cities sufficient to keep them functioning normally? Has this happened in Caracas? Where is all the Chinese and Russian food for Venezuela?
If the USA is in the thrall of anarchy/civil war, the rest of the world is going to slide into a depression. No country will be loading up ships with enough food to keep the blue hives from imploding.
Ditto fuel deliveries. China and Russia will have their own problems.