Good article, face recognition from that far however will be pretty complicated. To locate someone at the concert and guide would be best to use already present in Android Pie feature of locating someone based on its distance to wifi sources like routers, etc.
Even if they aren’t familiar at first, don’t underestimate the value of learnable icon sets. Consistency is important for creating learnable systems, as you point out; it’s also important to avoid icon-overload.
Once a designer starts adding icons to a system, it can be tempting to attach icons to everything.
Great article Nick! I agree, AR is the future, but it’s also good to aim for the next big thing Mixed Reality (MR) and Spatial Computing.
Btw, check out my article about it, with some of my concepts and ongoing development…