That would depend mainly on price. I imagine at this early stage pricing would be entirely speculative, but new technologies don't usually start out cheaper than established ones.

If it's fundamentally sodium vs. lithium then it's going to have huge price advantages at scale.

That's a matter of cost, not size. Mass is more important than volume for cost because transport depends on the weight primarily and because fundamentally more mass means more stuff. In the end you still have to pull x tonnes out of the ground.