There were once more than 700 languages

spoken by indigenous Australians. That is the estimate of academics who have studied them. It may have been more than 800. The estimates vary and there are, as always, discussions about what constitutes a "language" as opposed to a dialect or something else. Some of those languages were related to other languages. Many of them were spoken by just a few people. 
There are now about eighteen to twenty indigenous languages in every day use. If you could bring indigenous Australians from the eighteenth century into the twenty-first century and place them into groups which speak their language however they would not be understood. The language has changed. It had to change. Indigenous Australians didn't need the same vocabulary then that they do now. There is now no such thing as a "pure" indigenous language. 
Languages have to change or die. It is why the Oxford English Dictionary keeps on having to add words. It is why so many indigenous languages died out. There were too few speakers and they simply didn't have the vocabulary to describe the new world in which they found themselves. The new language began to take over.
When we lose a language we lose a way of thinking. We lose unique words and ideas, stories and connections. I have said this before but it is one of those big ideas which is worth repeating. 
There is now a struggle to keep alive the remaining indigenous languages. They are no longer the indigenous languages of the past. They can't be. There were no words for things like "car" and "television" and "computer" or "i-phone". The way people count has had to change, as does the way they describe familial relationships. There has been such a major impact on these languages that it is uncertain what is being preserved, particularly as no indigenous languages had a written tradition. 
On Australia Day it is said one of the local "pop" stars sang the national anthem in both English and a native language. Really? She sang the national anthem in English. She sang other words to the same tune. The meaning may have been similar  but it wasn't the same. I would be surprised if the words had been understood by more than a small handful of people. It was criticised as  being "tokenistic" and "politically correct", "meaningless" and "insulting". Given the attitude towards Australia Day of many people with indigenous links it might well have been "inappropriate" and, I would add, "inaccurate". Translation is a curious business. Meanings differ in so many ways. 
Language survival seems to depend on so many factors. Are languages worth saving? My gut reaction is that we should try to save all of them but my intellectual reaction is that we can't. What we do manage to save will not be the languages themselves but some sort of mutations of them. 
Is that going to be enough?