Oh cmon, this is minutes from the rest of the Apple buildings in the area, they aren't moving to a suburban campus, they are consolidating their suburban campuses.
You really need colocation to make things work. I expect two things out of this building:
First, it will improve a bunch of Apple's internal processes.
Second, they will run out of room sooner than they think, and I'd put money on them not even releasing leases on many outlier buildings.
This will take a long time to build and move into, but once they do, I wouldn't be surprised if they eventually manage to buy out that "missing piece" and incorporate it into the plan. One step at a time...