The failure case is still terrible and consists of me with a hacksaw at 3am on the side of the road "Stealing" my own bike.
a final note, the battery innovation does not even have to be that much of a breakthrough. if your phone lives for a couple of days on a single charge, then the probability of running out of battery will decrease dramatically (since most people charge at least once every two days).
Feel free to use something like this. It's geeky cool. I've just been burned by things like not being able to contact my ride from the airport, or my phone randomly deciding that it's just too dead to turn on at 8%, that I'm not trusting it for keys to my transportation / apartment.
For those things, if they have battery, like say my apartment combo lock, I want things with a good battery life (in the years) for the whole thing, a good failure state that I will always have on me (a combo), and obvious notification EARLY when the battery is going low.
There will be improvements, but they won't be easy or particularly fast.