Miami doesn’t have the infrastructure to move the massive amounts of goods. Down at the end of the peninsula, rail and highways are very limited. Out of Houston, there are massive amounts of rail lines, as well as multiple interstate highways. Tat is why Miami will remain a regional port, while Houston and Galveston are international ports.
If the final destination is the East Coast, the ships will go to other deep east coast ports as they do now. Texas will still get its share, but probably no more than the proportion it receives today. The big benefit for Texas and other gulf ports will be energy exports going in the other direction.
California port traffic is predicted to decline 10 to 15 percent.