We have examples of life in the most extreme and unlikely places right here on Earth. Near volcanic vents hundreds of miles below the oceans, in volcanic craters and mounts, Antarctica, miles underground under enormous weight pressure. Not to mention signs of past microscopic life on meteors that have fallen to Earth. There's also evidence of such life forming on Earth long before there was oxygen 4 billion years ago. So, I'm confident there will be life if not on Mars, then somewhere else in our solar system.