I understand that it's expensive. Toyota says it's 3K for replacement. They've had good enough luck with them that they've extended the warranty from 5/50,000 to 8/80,000. What does it cost to replace an internal combustion engine? A fellow I know at our local dealership says that since the Prius was introduced, they've only replace 3 battery packs. One was the result of a collision, one was the result of rodents getting into the wiring and one because it just went bad.
One off the reasons I think they're here to stay is because of the tremendous strides in battery output and life. But, because the infrastructure is not in place to province quick charging stations, hybrids make more sense than pure electrics. I've been a radio control flyer for the past 20 years or so and have seen first hand electric planes evolve from the small park flyers to to the size that most R/C flyers fly. Cost has come down to the point that an electric motor, speed control, and battery pack are about the same cost as a comparable size "glow" engine. And when 10% nitro fuel is $20 a gallon, being able to charge at home for just pennies is an added bonus. Okay, I'll quit now.