From the hard-negotiating mouse department:

Disney is in the process of negotiating a new contract with Port Canaveral because the ten-year term of their initial contract will expire next year. Today's Orlando Sentinel has an article about the issue. It's initially a little misleading, because you have to get a good distance into the lengthy article before you realize that there's little chance Disney is going to pack up and leave the port entirely. Aside from just negotiating new terms, because the old contract is expiring, a major issue in the negotiations is that Disney has two larger, new ships on order. That comes into play because the custom-designed terminal the port built as part of the first contract needs to be modified to accommodate the new ships, and Disney wants to maintain exclusive use of it. While no one really expects Disney to leave the port entirely, no one really expects all four ships to be based at the port either.