China, Russia and other countries will continue to avoid the necessity to gradually work towards being carbon neutral, which will lead to worldwide conditions that kill a lot of people.

Russia will continue to try to expand into anywhere that Putin wants, eventually resulting in the Americans trying to prevent this, resulting in nuclear war that will kill a lot of people.

I do not believe that even this combination of problems will result in the end of the human race.
When it becomes extremely obvious, totally undeniable, that everywhere on Earth should be carbon neutral it will occur and nature will recover the situation. A nuclear war between America and Russia will kill a lot of people in densely populated areas of the planet but nuclear weapons will not be wasted on the Arctic, Antarctic and desert areas, though some effects will be spread by wave and wind etc. In all of those areas there will be lots of small communities, in total probably several hundred thousand.

I do not believe that all human beings will be wiped out by human action or inaction. Starting from a small base we would go on, in the very long term it is just a 'haircut'.

Of course we could all be wiped out by the result of a seriously large asteroid hitting the Earth but we now have the technology to detect this possibility at an early stage. Thus the most powerful regimes worldwide would collaborate to solve the problem.