The language reflects the adaptations of a culture to survival in a unique environment. A certain richness of the human tradition is lost when a language is lost. One probably can do nothing, and perhaps one should except in certain circumstances do nothing, but that does mean that the loss should not be noted and mourned.
The way we are headed we will all be speaking a peculiar stilted form of English in the barely intelligible dialect of East Asians. Fortunately, I think that the human spirit will not allow that to happen. Even though people around the Baltic Sea speak English better than you and I, things like Finnish and Estonian are surviving just fine. It is necessary. The English language does not have an adequate way of describing the experience of a Møøse bite.
That’s the funny thing about knowledge. When you loose some of it, you never know what you might have missed.
A language is, in essence, a human art form. If the Mona Lisa disappeared tomorrow, what loss would that bring? In concrete terms - nothing.
But not everything can be measured in dollars and cents or inches and pounds.
These dying languages are a link with our common human past and all efforts should be taken to record all of them and assure the information contained therein is available for future generations.