I think there's a non zero chance that in the relatively close future some form of microscopic life may be found by a probe on Mars or Europa. But would that really change much for humanity?
Even if the conditions for the emergence of life are very rare, the universe is such a mindbogglingly enormous place that there are probably an immense number of planets with life in it, sentient life may be much rarer, have a tendency to self destruct along the way and the distances in time and space so enormous that any sentient species may never encounter each other.
I think it's fascinating and sad to think that there may be millions of civilizations that we couldn't even begin to imagine that have risen and fallen before we ever came to be and that will come along long after we're gone. But unless one really advanced finds us and decides to reveal themselves, I don't see much of a chance of us ever encountering one before we destroy ourselves.