What if mitochondria begins to evolve and can't be used as a factory to produce ATP, if this mutation in the mitochondria spreads, will the human race die out?

Yes, along with all aerobic eukaryotes (that's pretty much life as most people know it). Obviously, each of us has their own mitochondria, and there really is no way such a harmful mutation would be able to spread. You'd have to have a virus that could infect the cells and mitochondria inside them to change it.

maybe it occurs in a gradual way, possible. if you consider a sudden shift from ATP producing to non-producing and remains at advantages, there is a problem (error!) of saltationism.

There are a number of mitochondria-related diseases. However in case of lethal mutations (or anything that abolishes reproductive abilities) they obviously cannot spread through the population.

Yes, along with all aerobic eukaryotes (that's pretty much life as most people know it). Obviously, each of us has their own mitochondria, and there really is no way such a harmful mutation would be able to spread. You'd have to have a virus that could infect the cells and mitochondria inside them to change it.

 

So, what about a kind of ERV, infects the mitochondria, then this ERV incision lays dormant until it is passed on to a future generation. Most of the human race is infected, then a few decades later, everyone is dead.

 

Is this even remotely possible?

What if there are variants of your ERV so that it doesn't kill its host? Wouldn't it confer the variant an advantage over others? So host is the vector how the virus propagates, if their burst kills all of their host, they're doomed to extinction. Yet if they didn't affect their host to help their propagation (like most of the symptoms of sneezing, coughing.etc), they got weaker propagation capacity and would be overrided by other intraspecific competents. There hence always an ideal equilibrium position (ratio) between virulent forms and milder forms. Even in your presumed example, the affected species would not go extinct.