After substantial thought on the topic by various smart people, the answer seems to depend on the ultimate nature of physics and ultimately the ultimate end point of engineering. If leaving planets is engineering-impossible and we can't fling even small projectiles out of the Solar System at any reasonable fraction of lightspeed, then it's of primarily intellectual interest. If the Singularity is impossible and humans will remain recognizably human for the indefinite future but it's possible to travel between the stars enough to actually colonize things, eventual war of some sort seems pretty likely in most situations, though not necessarily to extinction (though not necessarily not!). If a Singularity is possible and looks something like Accelerando, the future of humanity may be an enormous set of entities of such incredible mutual alieness that meeting another set of such entities from another biological base may be of no particular note, locally exciting, globally ho-hum.
I haven't expanded much on the thinking behind these, because I mean them merely as examples of my main point and if I go on too long about them it becomes very tempting to miss it in a flurry of nitpicking about the details of various scenarios. My actual point is that we don't really know what happens, because we don't know what those engineering limits will be. There are some scenarios where the universe naturally favors species getting along, and there are scenarios in which the universe naturally favors species attempting to extinguish each other with all possible speed.
Assuming no ETs exist within our 200ly bubble, if ETs somehow discovered our signal and made contact, our level of knowledge would jump a few centuries at least.
I haven't expanded much on the thinking behind these, because I mean them merely as examples of my main point and if I go on too long about them it becomes very tempting to miss it in a flurry of nitpicking about the details of various scenarios. My actual point is that we don't really know what happens, because we don't know what those engineering limits will be. There are some scenarios where the universe naturally favors species getting along, and there are scenarios in which the universe naturally favors species attempting to extinguish each other with all possible speed.