Even our feeble efforts to poke around our own neighborhood have shown us places off Terra where life could exist. Life is tough, adaptable, persistant and sneaky. We've found it thriving in places that were "impossible" when I went to school. As chemistry it's almost inevitable. Inteligence might be another mattter. Big brains could be the doom of our species unless we use them better than we have been. Any critter with enough smarts to make a fussion bomb ought to have the good sense not to.
If that turns out to be the case then we will stumble across our cousins' electronic tracks somewhere out there - and they will find ours. When we do find ETI the very core of the first message will be "YOU ARE NOT ALONE". That should shake us out of our smug center-of-the-universe thinking. It will certainly shake up the boys in the funny hats (turbans, yarmulkas, miters and the like).
Considering what that bunch wanted to do to Galileo (they only let him out of Hell a few years ago!) the folks at SETI might want to make the announcement from somewhere safely out of reach.