All that depends on whether or not the protocol is still alive. There are two documents governing this event at the moment. The DoG that basically says that as long as the defender and challenger are in agreement, anything goes. It also has specifics about what constitutes a valid challenge and how they are ordered/accepted. Then there is the protocol most recently agreed to by the defender and Australia under which two teams have signed up (Luna Rossa and I forget who else). If that protocol remains valid, then it is still the master document defining the event. If, for some reason, that protocol becomes invalid, then we're back to the deed of gift.

As I understand it, there is a minimum number of challengers needed by a certain date in order for the current protocol to survive (I think they need two or three more paid up in the next couple of months). This is defined in the current protocol that Australia and Oracle negotiated. IF that happens, the protocol is still in place and the next challenger was the next guy that has already officially entered and been accepted under this protocol. If that doesn't happen, the protocol evaporates and we're back to the basics of the DoG and then the question becomes did someone else submit an official DoG challenge after Australia?