Yes, it is inevitable that the human species, as we know it, will become extinct, no matter how hard we try to keep the "evolutionary degeneracy" to a minimum.

Which we can do by ensuring that everyone marries someone according to a plan, that "spreads the deviation" around so there are no sub-species.

If you are confused by this answer, you need to understand how evolution works - even in species that APPEAR to not evolve.

All DNA has errors in duplication. The "purpose" of sex is top ensure that deviations are minimised, by having two sexes that duplicate what the species is supposed to have, in terms of DNA. MOST errors in one sex are corrected for by the other sex.

But there are two problems. The first is that of "sub-species" - like Homo Sapiens and Homo Neandertal, or like chimpanzee and bonobo. All it takes is for "West Africans" to evolve separately from "North Europeans" for a few thousand years - and in this case, the "North Europeans" interbred with Neandertals, and you have two "races", and if you continue with the separation for longer, as we had with our Neandertal cousins, and you have sub-species of human beings, and two species of apes that WE PRESUME can't interbreed at all - us and bonobos or us and chimpanzees.

Note that I said "we presume". The difference in the number of chromosomes between bonobo (48) and human(46), doesn't stop horses and donkeys from interbreeding "mules", with the very rare but possible fertile one.