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.
People imagine Kessler as one of those things that happens instantaneously. It's much more likely to happen over several decades. There's a good chance that we'll be able to stop it while it occurs through one of the very expensive mitigation measures that have been proposed.