From the understanding of the mechanisms that cause this invariance, many other applications could be derived, that even don't need the invariance property. For example materials of which cooling systems (e.g. Peltier-like) can be made. Also their measurement methods seem pretty advanced and could be used within other research like in the area of nano technology.
Yes, the main value would probably be in better understanding the temperature / pressure / volume / magnetism relationship within invar-like materials. Perhaps the result will be new piezomagnetic applications, or magnetocooling applications, and so on.