"One function of elevator cables is the emergency brake system "
With this maglev system (as with conventional elevators, trains and trolleys), there is a speed governor system. When the governor spins too fast, the centrifugal force activates a braking system.
I'm not sure how the elevator works, but if you've ever tried to toss a magnet down a copper tube, it appears to defy gravity - no electricity involved. Something similar could work to create a "fail-proof" elevator.
Please not. I wouldn't want to put my life in the hand of a (hopefully charged) battery. Any failsafe in an elevator must be mechanical and work with total loss of power. Anything else would fail at some point. This happens with other product at some points. But elevators are one of the few products trusted by nearly everyone because they never kill anyone.
That's only for the first version. It's not unlikely that they can compete by price in the future. First versions of a new technology are (nearly) always more expensive than the existing, mass produced product.