Was just reading through the articles I could find about it and it seems you can't make cylindrical batteries with it. Which sucks for existing flashlights. I'm sure if the tech ever picks up some other shape of flashlight could be made.
There are cylindrical cells available. The capacity is pretty low, 18650 cells are around 1.5AH and 26700 cells are around 3.5AH. They discharge down to 1.5V, so you will get less capacity if you use them in something designed for lithium cells.
They are actually better than Lithium in several ways. Sodium batteries have most of the capacity of Lithium batteries by weight, around 80% if I recall. But what they have to offer is being completely non-flammable, tolerant to wider temperature ranges, and they are made of materials that are cheap and abundant almost everywhere. It's much better than having to source Lithium and Cobalt.
We could put Sodium batteries everywhere to power the grid since they are super safe, should be fine outdoors even.