Kessler syndrome is one of the things that give me that dread feelings, one of the things vast majority of people can do nothing about, yet it can derail any dreams of extra terrestial endavours before we even reach that point.
replies(3):
In 200 years, we will have tamed the ability to generate energy efficiently and have relatively intelligent drones. These drones in swarms can track space debris, match their horizontal speed and push them out to outer space. Space debris will not be an issue. Maybe they can also take little bubbles of greenhouse gases and drop them out into space too.