At this point in your story, it would be alright to call "degrowth" what is really is. Economic contraction. Recession. Not just two quarters of negative GDP growth but on going and continuous negative GDP growth.

When you look it that way it is easy to see why leaders are not interested in "degrowth." It is not going to be popular to advocate for a never-ending recession. Voluntary austerity. Kicking the can down the road is a very attractive alternative. You don't mention when it becomes impossible to kick the can any farther down the road.

2050 is a common carbon neutral date. That does not mean no fossil fuels just no increase in CO2 in the atmosphere. Emissions are offset by uptake. IF we run out of oil the no oil will be the least of our problems. Some of that oil needs to stay in the ground to save the climate. Even if we stopped burning fossil fuels today sea-level rise will continue into the next millennium. The crisis is already baked in and while we should continue with mitigations, we need to work much harder on adaptation. It is not fair but rich nations will be much more able to adapt. They will probably adapt at the expense of poor nations. The poor will get poorer faster than the rich will get poorer. We are fast approaching peak wealth.

TEK