There are improvements but physics and chemistry kick in at some point. I don’t know enough to presume where that point is, but you seem to be presuming that the limits for sodium will be better than lithium and I’m not seeing any evidence provided, just faith. May as well work with the reality we have while we see how that pans out. Like someone else said, we recycle a lot of lead from lead batteries, we didn’t stop when lithium batteries came along