There is no guarantee "intelligent life" is going to last much longer than any natural life form.

In fact, the rythm at which living organisms disappear on our own planet and because of our interference is an indication we might be the instrument of Earth's later life extinction.

We were Earth-centered, till Copernicus; we're now Human-centered (thanks to religions, for instance) and therefore we will end up all alone, on our own planet and by then it will be too late anyway.

Intelligent life, what is it? One capable to sustain itself in the very long term or one capable of creation and therefore destruction to such a scale that its extinction is enormously accelerated?