I am hoping for a breakthrough where they can pack more power into less weight.
I read recently, in a technical newsletter I receive, about the development of the lithium-sulpher battery. It has four times the power to weight ratio of the present day Li ion battery. So, we could either reduce the weight of the battery by a factor of four and go the same distance or stay the same weight and go four times farther. A nice choice to have! Further more, the battery won't flame if over-charged or over-heated. It didn't say anything about physical size, compared to Li ion, however.
The university that developed the lab model said it would be easy to put into production since there was nothing difficult involved in construction.
I hope they don't hit any unforeseen technical "snags" that would kill the development and that we hear more about this soon.
Trikester