Is that something that can catch up, or is it simply a density issue that can't be terribly optimized?
Right now it looks like it takes ~75% more space for the equivalent power... after two decades like Lithium-ion has had, can that reach current density/size for the same power, or will it hit a cap?
Still nice to see a battery tech hit the market.
Both chemistries are likely to continue to improve. And sodium ion is still pretty new. There might be some solid state batteries based on sodium ion at some point. Lithium ion solid state batteries are much closer to market ready (multiple manufacturers have announced product roll outs over the next few years).
For a lot of use cases, cost and safety might be more important than energy density. There are a lot of different chemistries at this point.
This device is a bit on the heavy side but not overly so. 350 grams is not that heavy. Probably price and longevity are more decisive factors for people that would buy this. And the safety is a nice bonus.
With less thermal management problems, maybe the packaging of sodium-based batteries may end up turning better (lighter, more compact) than lithium ones. That is a way how in theory it is worse, but in practice it isn't so.
Sodium batteries will probably be the go-to for grid scale battery in (wild guess) ten years and some of the ultra-cheap electronics. Sodium, Li-ion and lifepo4 all have significant overlap in the 2.5-3.7v range so there's a lot of potential for compatibility/interoperability
Compare with lithium batteries, which currently there's only a handful of high quality lithium deposits that are convenient to be mined
I hate to break it to you like this, but the oceans will evaporate in about a billion years.
https://en.wikipedia.org/wiki/Future_of_Earth
We should still have the sodium, though.