Forget flying drones. When it comes to predictions on what sci-fi method might bring you hot pizza, aspirin, groceries or new shoes, some experts bet that delivery robots rolling down sidewalks will beat out airborne couriers.

To hear Port of Oakland, California, officials tell it, losing terminal operator Ports America — a major tenant — is a blessing in disguise that will create a leaner, meaner seaport. But some maritime experts say the fallout could hurt the port, a vital economic engine that supports tens of thousands of jobs related to overseas cargo.