That is not a controversial thing to say.

> The background level of extinction known from the fossil record is about one species per million species per year, or between 10 and 100 species per year (counting all organisms such as insects, bacteria, and fungi, not just the large vertebrates we are most familiar with). In contrast, estimates based on the rate at which the area of tropical forests is being reduced, and their large numbers of specialized species, are that we may now be losing 27,000 species per year to extinction from those habitats alone.

> The typical rate of extinction differs for different groups of organisms. Mammals, for instance, have an average species "lifespan" from origination to extinction of about 1 million years, although some species persist for as long as 10 million years. There are about 5,000 known mammalian species alive at present. Given the average species lifespan for mammals, the background extinction rate for this group would be approximately one species lost every 200 years. Of course, this is an average rate -- the actual pattern of mammalian extinctions is likely to be somewhat uneven. Some centuries might see more than one mammalian extinction, and conversely, sometimes several centuries might pass without the loss of any mammal species.

https://www.pbs.org/wgbh/evolution/library/03/2/l_032_04.html

It can of course be summarized in the words "nothing lasts forever".

And as to why it would apply in the future - entropy.