It'll be interesting to see whether there might be any kind of late-mover advantage for those who sat out lithium and begin pursuing sodium-based batteries now.
Sodium is good for stationary deployments. It's not good when weight matters.
Add water to elemental sodium, and you get heat, hydrogen gas and sodium hydroxide.
As you know, each new chemistry (and anode, cathode, etc) opens up new niches, use cases, and price points. Sodium won't displace so much as compliment lithium.