The Far Distant Future. The time scales mentioned here, which represent Deep Time, a concept only rarely found in science fiction (most of which is set only a few centuries in the future), are the future equivalents of the Middle and Late Pleistocene, the Pliocene and Plestocene, and tree-quarters of the entire Cenozoic (or 500 thousand, 5 million, and 50 million years in the future). Two scenarios are presented here: The Long Decline (long term) and Posthumanity.
The long decline: (long term). This is the continuation of the the Long Decline (medium term). As paleontologist Peter Ward points out, humanity is basically extinction proof, and so lingers on, still scraping a miserable living from the Earth, perhaps like the dustbowl conditions of the 1930s in America. This means that, unlike in previous mass extinctions, the biosphere is not able to recover. Eventually, after who knows how many million years, becoming extinct, humanity does die out, leaving an impoverished Precambrian-grade biosphere behind, which itself disappears as the increasingly heating and aging sun makes conditions on Earth impossible for all but extremophile prokarytes
Posthumanity: (long term) in this time frame will be unrecognisable to the “baseline” humans of today. Posthumanity can, but does not have to, involve advanced tech scenarios. It could also involve retro-evolution. An example of this is presented in Man After Man: An Anthropology of the Future is a 1990 work of speculative evolution Dougal Dixon. It follows the hypothetical future path of human evolution from 200 years to 5 million years in the future, with future human species evolving through genetic engineering and naturally. On Earth, modern humanity is replaced by unintelligent human species, including herbivores, predators, and even parasites. For more see Speculative Evolution Wiki.
Dates from Bored Panda (33 Things That Will Happen To Earth In The Next Trillion Years According To Scientists)
Page by M Alan Kazlev, 2023