Unfortunately what's shipping today seems it would offer maybe half that.
For the batteries that were announced this past week, a larger-than-refrigerator-sized cabinet held a capacity of around 15kWh.
Around half the energy density by mass of Lithium batteries, and in the order of a sixth of the density by volume.
Now if only we could come up with a system where your car could be charged while stopped at traffic lights, we might be onto a winner (:
Considering however that the price of sodium is around 1-2% that of lithium, I expect we will see significant R&D and those numbers quickly start to improve.
Probably best to look at it as a competitor to a Xeon D system, rather than any full-size server.
We use a few of the Dell XR4000 at work (https://www.dell.com/en-us/shop/ipovw/poweredge-xr4510c), as they're small, low power, and able to be mounted in a 2-post comms rack.
Our CPU of choice there is the Xeon D-2776NT (https://www.intel.com/content/www/us/en/products/sku/226239/intel-xeon-d2776nt-processor-25m-cache-up-to-3-20-ghz/specifications.html), which features 16 cores @ 2.1GHz, 32 PCIe 4.0 lanes, and is rated 117W.
The ostensibly top of this range 4584PX, also with 16 cores but at double the clock speed, 28 PCIe 5.0 lanes, and 120W seems like it would be a perfectly fine drop-in replacement for that.
(I will note there is one significant difference that the Xeon does come with a built-in NIC; in this case the 4-port 25Gb "E823-C", saving you space and PCIe lanes in your system)
As more PCIe 5.0 expansion options land, I'd expect the need for large quantities of PCIe to diminish somewhat. A 100Gb NIC would only require a x4 port, and even a x8 HBA could push more than 15GB/s. Indeed, if you compare the total possible PCIe throughput of those CPUs, 32x 4.0 is ~63GB/s, while 28x 5.0 gets you ~110GB/s.
Unfortunately, we're now at the mercy of what server designs these wind up in. I have to say though, I fully expect it is going to be smaller designs marketed as "edge" compute, like that Dell system.