Debbie might be saying it in 5 years too. I would say she will be saying it every year until she's finally right. My sense is that before she's right with respect to real battery advances showing up in mass-market cars, it will be 6-12 years.
I would say 12 years based on the normal time to get something from the lab to mass market, but the appetite for this is so strong and the first-mover advantage so great, I think it will happen much faster. This isn't like, say, SSD drives replacing spinning platters.