12v batteries probaby, but EV I'd doubt it considering how much range was a major hurdle to overcome. More weight, less range with the same capacity, meaning you need to add even more capacity, which reduces the space available for everything else.

My vision would be Li-ion will still be the king for medium to high-end EV, but for low-end EV, or those for whom range isn't as much of a problem than for other (short range commuters) that would indeed be a game changer.

In my case, a 300-400 km range sodium-ion battery car, with a decent fast charge (less that an hour from to 80 percent) would be ideal. I use trains for anything further than that, and my car is mainly used for short range duties (less than 40km a day), once or twice a month. For anything closer than 20km I got my trusty cargo bike (which I use extensively, 2700km last year).