There is no great solution because these fires are self-oxidizing and produce a hell of a lot of heat. If you could blow it apart with a bomb then that might spread the stuff out enough for it to quickly burn out. But other than that all they can do is wait for it to burn out and maybe cover it. Metal fires such as those in these batteries are uncommon but far from new, yet nobody has found a solution in decades.

I imagine if one of these goes up on (or under) a bridge, it'll compromise the bridge if it can't be extinguished. This happened some years ago with a (diesel) semi in Oakland, I recall, and it sounds like these burn much hotter.

That is a really good point, just a matter of time until a EV Semi catches fire under a bridge or overpass and causes massive structural damage.

Or a parking lot full of unextinguishable EVs under a high rise... The potential fallout from arson is astronomical due to how bad these fires are.

The solution will be to move to a safer energy storage system.

Solid state batteries as supposedly safer.

Better is a relative term when it comes to this issue. Batteries must be chemically unstable in order to be recharged (as I understand it) so practically any battery with high enough energy density is subject to that kind of event.