Also, we should remind ourselves that we live on a planet with limited physical resources. So, assuming that we build something that could exponentially out-smart us, that thing would still need to have access to physical resources for which what is available on this planet might not just be enough. I see it 2 ways: the thing/it/whatever we want to call it either manages to expand from this planet/solar system before it auto-destroys itself, or it just dies off for lack of available resources.