We have found life on this planet in places we thought totally uninhabitable. We have found single cell organisms living a mile or more below the surface, living in rocks. We have found flourishing life on the sea floor surrounding volcanic vents and living off of the sulfur. And as scientist wonder whether or not there could be life on the moons of Saturn or other alien places, we have to wonder if there could be life in an environment that is primarily ammonia and methane, for instance. We don't know yet what the extent of life is on our own planet. We have almost no way of exploring the possibilities of very alien life in other places here in our own solar system. And no capability, other than detecting instrumentation that is biased automatically because it was built by humans, that might not detect life forms that are unimaginably alien.
I've little doubt that we'll have to widen our definition of life as we find out more about the universe. Sadly, things are going to slow for me and I'll be long gone before we find anything really exciting. But it is fun to think about.