They say they will be 15000teu Ted.
But that will include a lot of "hot air".
From what I understand they will get a rather unusual length to width ratio of 21 40ft bays long and 21 boxes wide, but I haven't seen any plans let alone pictures yet.
Now it's waiting for the first picture here of something light blue from the premises of Hyundai Heavy Industries.
Cheers,
Roy