Sagan always said we had the potential to be better, but he was also concerned it was an uphill climb. Where Carlin got angrier with age, I think Sagan would just have been disappointed in us. Especially in the fall back into ignorance and superstition, something else he warned about in The Demon-Haunted World. Every quote you can find from that book is profound, but this one is eerily hard hitting:
“We’ve arranged a global civilization in which most crucial elements profoundly depend on science and technology. We have also arranged things so that almost no one understands science and technology. This is a prescription for disaster. We might get away with it for a while, but sooner or later this combustible mixture of ignorance and power is going to blow up in our faces.”
And any other species’ chance. Given the expected lifecycle of the Sun that will affect the habitable zone we’re in, we have just under a billion years to go before the planet becomes unlivable by anything. Is that enough time for life to start over from some point and try again? Presuming minus a hostile period of time while Earth finds a new environmental balance, which always takes a while.
I think for whatever odds there are out there of other planets that can have the right conditions for life to become intelligent and expand further, they get one shot at it. If there were alien observers they’ve probably stopped by now. “That went like usual. Got close, but they did the typical mistakes.”