The best possible business apps, including the Thyssenkrupp promo, revolved around conferencing with people in real time in an augmented reality space. Someone can help you while viewing what you're seeing, and interact with you using holograms, files from your OneDrive, and of course video chat. The Skype demo is by far the best implementation I've seen of this, and it's designed really well imo. The other user does have to download a skype plugin, but then they are able to interact with your space.
I've yet to test it with two devices, but there's a lot of shared experience functionality in the HoloToolkit.
The Skype call will use the forward facing camera of the Hololens user. For the Hololens user the view of who you are calling will be presented in front of you as you move around. Also, people on the Skype call can interact and draw on objects in front of you.
I haven't used it, but I feel fairly certain that the killer app for VR/AR is going to be eye contact. Skype with eye contact would be a major leap forward. Eye contact lets you negotiate speaking/listening handoff in a natural way, instead of using awkward procedural norms.
