The logistical issue is that the largest container ships can not fit through the Panama Canal. So, even if your container of “X” coming from China is going to Chicago or Buffalo, it might still be cheaper to ship it to LA and unload it there. Before shipping it across the country. Generally, container ships going to the east coast from Asia all can fit through the canal.
What will change eventually is the cost of trucking out of California. The people that will get screwed are the consumers in CA, AZ, NV and others close in proximity to those ports.
Is there a container ship port in Mexico that can take the largest ships? Somewhere on the north end of the Baha or Sea of Cortez? Maybe the Cartels and Chinese can build one there.
Something to consider here is that the Panama Canal has actually become LESS important for containerized cargo over time. There are a couple of factors at work here:
1. In many industries, high-volume manufacturing in Asia has slowly migrated south and west from China, Japan, Taiwan and Korea to places like Malaysia, Indonesia and Thailand. Singapore is the "centroid" of Asia for supply chains to North America. It's almost exactly equidistant in either direction to the East Coast of the U.S. from there ... so shipping to the U.S. from posts west of Singapore is more efficient via a westbound water route through the Suez Canal than eastbound through the Panama Canal.
2. California is a major consumer market itself, but most of the cargo coming through the LA/Long Beach port complex is destined for other parts of North America. In many respects, those ports may be more of a nuisance than they are worth -- especially when you consider the local impacts of traffic congestion, noise and diesel emissions.