From the Journal of Commerce:

A massive shift in market share on the east-west trades is in the pipeline as the order book of the Ocean Three (O3) and 2M alliances will see their combined mega-vessel capacity eclipse that of their more established G6 and CKYHE rivals.

The three O3 carriers have ultra-large container vessels on order that will allow them to maximize economies of scale on their combined services. UASC has six 18,800-TEU ships on order and China Shipping is awaiting delivery of five 19,000-TEU units, which will be the largest container vessels afloat. CMA CGM has six 17,700 to 17,800-TEU units on order, scheduled for delivery in 2015.

More at the JOC