If the report is predicting 100 years in the future, are we really "to the brink" now? Not to mention the decay time of these LEO is in months, hardly a kessler syndrome scenario.
It probably doesn't matter. Global warming has proven that we are incapable of doing the necessary things to slow or stop the human-caused decaying of our planet. I'm starting to think we deserve what we're gonna get.
The report says we will be in trouble in 10-20 years, not 100. Look under "collisions causing collisions". Debris from previous collisions increases the risk of future collisions.