From a JOC article titled ‘Designers advancing plans for even bigger mega-ships’:

The next generation of mega-ships is already in the planning stages, despite hesitation from some of the world’s largest shippers about their overall value and feasibility.

While designers are working on larger vessels, the prospects for those ships in the market remain unclear. The jury is still out on mega-ships and their impact on ports. While the ships do result in increased productivity at berths worldwide, they are causing congestion problems at terminal truck gates. As a result, ports are seeking ways to improve their operations.

More at the Journal of Commerce