We just integrated the latest Nordic nRF52 BLE chip and made possible for proximity beacons with built-in programmable NFC. Beacons support iBeacon or Eddystone/Physical Web and might be a nice toy to play with latest Google Instant App Downloads via NFC/Physical Web feature.
Happy to answer any questions here.
Using it as a key? Not that much easier to use than a smart card/NFC. A fair amount of consumer education required for adoption. Not available to all consumers, all the time.
Tracking? I find the price for beacons and the restriction of range makes other solutions more practical.
Location-based triggers/actions (ie walk into a room, light turns on).. Tech and solution exists without your product. A phone has GPS and actions can be taken based on boundaries..
The single best place I can see this applied is to the shipping industry and daily ops tracking of very high value products. But it seems like a very small, and obvious use-case.