- Destruction of the planet itself: Well-nigh impossible.
- Destruction of all terrestrial life: Very difficult.
- Destruction of all human life: Difficult.
- Destruction of our civilisation and of the conditions under which large-scale human civilisation is possible: Possible.
- Significant decline in human population and/or biological diversity: Fairly likely over the long term on our present path.
- Downfall of/significant departure from the present mode of our society: Likely and probably imminent in the next few decades.
- The ongoing catastrophe of history that we call progress: Presently underway.
What can we do? Byron Smith has another post that points us in the right direction: "Twelve responses to converging crises".