I’m amazed it’s taken this long for one to be lost.

Ukraine's been constructing decoys, and there's a Czech company that's been building decoys as well. I'd imagine that some of it is weapons being used on decoys.

We should send a dozen more to compensate.

Apparently we deactivated a HIMARS battalion today.

https://www.marinecorpstimes.com/news/your-marine-corps/2024/03/05/marine-himars-battalion-to-fold-amid-overhaul-of-corps-artillery/

Marine HIMARS battalion to fold amid overhaul of Corps artillery

A Marine rocket and missile battalion with a legacy stretching back to World War II is set to deactivate in March as part of an effort to modernize the Marine Corps’ artillery.

The battalion was the first in the Corps to be dedicated to firing the high mobility artillery rocket system, or HIMARS.

Now, the Marine Corps is prioritizing a ground-launched anti-ship missile capability, the Navy/Marine Corps expeditionary ship interdiction system, or NMESIS, which means the active component is divesting of some HIMARS, according to Marine spokesman Maj. Eric Flanagan.

I don't know how many launchers they have.

https://en.wikipedia.org/wiki/5th_Battalion,_11th_Marines

That says five batteries.

If you figure that the launcher allocation is the same as the batteries that Poland is putting together:

https://defbrief.com/2022/05/26/poland-buying-500-himars-launchers-for-over-80-batteries/

Poland has announced its intention to buy an additional 500 M142 HIMARS launchers that would equip more than 80 Polish Army batteries.

...then maybe six launchers per battery, so maybe thirty launchers that I assume aren't going to be used any more.

It looks like the NMESIS that they're switching to is some kind of smaller, unmanned launcher:

https://en.wikipedia.org/wiki/Naval_Strike_Missile

The NSM is to be used by the U.S. Marine Corps as part of the Navy/Marine Expeditionary Ship Interdiction System (NMESIS), which places an NSM launcher unit on an unmanned JLTV-based mobile launch platform to enable the Marines to fire anti-ship missiles from land.[25][26]

https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/NMESIS_launcher.jpg/1920px-NMESIS_launcher.jpg