>So - you're saying the expansion is becoming obsolete before it's even been completed? Not to mention China would probably like to have shipping lanes to Europe that are outside direct US control. And Nicaragua would no doubt appreciate having a powerful economic ally interested in keeping it out of US diplomatic control.
Not obsolete for quite a while. The US East Coast is farily small volume in international shipping. When these new ships come out, they don't suddenly replace every ship on the market. They cost in excess of $100m each and take forever to build, a ship order of 8-10 can take 5 years and there's only a few companies capable of building them. Meanwhile, ships last up to 40 years. The biggest ships get used on the highest volume trade lanes (Asia-Europe, Transpacific), the previous bigger ships get pushed down a tier, and so on. It can take half a decade to a decade to build a shipping terminal, several years to deepen with dredging for a shipping terminal, and is incredibly expensive to upgrade equipment at current locations. The biggest problem with these big ships though is that they have to run near full capacity to actually be profitable to run, and you simply can't do that on the East Coast right now because of market segmentation and lack of volume.
The economic interest in central American canals is not about trading with Europe for China, they can do that through the Suez Canal which is closer, cheaper, and handles ULCVs. The market for the canals are the US East coast, the carribean, and northern Brazil. The ships currently on those trade lanes are not very big, but more importantly, less in demand than Asia-Europe trades, so it won't get priority on the new big ships. Any significant change in that dynamic would take decades, as would the infastructure to support it.