The scientific definition of "species" is surprisingly complicated.
As this November 2017 article from Science News explains:
At first glance, “species” is a basic vocabulary word schoolchildren can ace on a test by reciting something close to: a group of living things that create fertile offspring when mating with each other but not when mating with outsiders. Ask scientists who devote careers to designating those species, however, and there’s no typical answer. Scientists do not agree.
For the sake of this question, though, let's just go with this definition from Berkeley: "a group of individuals that actually or potentially interbreed in nature."
Evolution marches on relentlessly. We homo sapiens – even armed with our technology and collective stored-and-shared wisdom--are not immune to this ceaseless force. At some point, our descendants will be so physically different from us – due to natural selection, human-engineered tinkering or both – that they would be properly classified as a different species. This Scientific American article explores some of the key ideas behind this question.
And of course, we might well kill ourselves off, replace ourselves with AIs, etc.
How many years from now will the last member of homo sapiens be born?
We'll consider the people the future creatures will succeed or fail to interbreed with as early 21st C humans, and this must be possible without technical intervention. The people must exist IRL, i.e. not be simulated beings, uploads, etc. As usual we contemplate beings in the same universe, branch of the wavefunction, etc., as the server running the copy of Metaculus the question sits on.