Someone else can certainly answer in more detail but I believe there's still a considerable amount of interior work to be done. Also, I think one of the exterior freight elevators is still up on the (southeast?) tower. So that's gonna have to come down. It's always such a tease when exterior work is completed on these projects because there's usually still at least a year's worth of work before they open.
Anyway, I'm not an expert on the topic. Just an enthusiast