Wifi has always been the obvious solution to indoor location (lower power than GPS / works indoors / piggybacks on installed hardware / somewhat "open") but fidelity was too low.
Hence the rise of beacons.
Beacons IMO are the least elegant solution to the problem of indoor location because they require (a) a whole separate location framework (b) requires vendors / stores to install & maintain hardware to drive coverage (c) are owned by the OS.
I've been watching this game unfold for years - Apple bought WifiSLAM in 2013 to improve indoor location / wifi (1), and then bought "super accurate GPS" firm coherent NAV last year. (2)
There are also several startups attempting to use sensor data + geomagnetic or inertial navigation to solve this problem. (3)
If these guys actually got Wifi working, and figure out a way around the callibration problem, they in one fell swoop solved one of the major barriers to the hyper-localized advertising / consumer tracking that we've been promised (threatened with?) for years.
(1) http://www.theguardian.com/technology/2013/mar/25/apple-buys...
(2) http://blogs.wsj.com/digits/2015/05/17/apple-buys-gps-firm-c...
(3) http://www.navisens.com/, GiPStech.com, http://www.PathSense.com, https://www.indooratlas.com/