Chemically, Sodium and Lithium are very similar, so any improvement that applies to one should be pretty applicable to the other. That’s actually one of the main strengths of Sodium batteries - most of the research that’s already gone into making Lithium batteries can be reapplied with minor tweaks. However, Sodium is inherently larger and heavier than Lithium, with fewer atoms fitting into the same space and those atoms weighing more. If research for Sodium batteries catches up with Lithium ones, they’ll still be worse just because of that, and at that point, research would get easier gains from improving Lithium batteries than Sodium ones.

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