If life can exist in these deep anaerobic levels, it certainly does seem plausible that it can exist in non-Earth planetoids, planets and moons.
Hoe will the discovery of life elsewhere affect Man’s own story of his existence?
I personally don't think that scientific discovery of life off the planet Earth would embarrass cultures or religions whose story of Mankind began including the phrase 'Let There Be Light', but those Creational stories dealing with Mankind springing to life from the shell on the back of a giant sea turtle or the falling leaves of the Five World Trees or even Zeus' orders to Prometheus may be looked upon with some healthy skepticism.
Mere discovery of extraterrestrial microbes wouldn't automatically invalidate the story of Brahma springing forth from a lotus flower in Vishnu's navel, I don't think, since the story is so abstract as to not necessarily run afoul of science.
I hate to sound like I'm making a dodge or an apology here, but I've always thought that 'Let There Be Light' perfectly walks hand in hand with the modern scientific theory of the creation of the Universe, right down to the very first instant.
Scientifically, I defer to everything that Einstein -- may he rest in peace -- said about religion with nothing more to add. Shalom.