Regarding simply transiting through our ex-satellite rings, I don't think there is consensus. Would it make launches beyond LEO practically impossible, or just theoretically risky in the way that blindly navigating the asteroid belt is? (You could hit something, but it's so little matter dispersed over so much space it'll probably just be extremely fine dust the shielding can handle. Probably.)
For example: two satellites collide head-on at an altitude of 300km, creating two debris clouds that extend from 250km to 350km. Each of those catches another satellite, one at 260km and another at 320km, which fragment into debris clouds reaching from 200km to 370km (all numbers made up).
Higher orbits, like geosynchronous, have a lot more space to work with and much slower relative velocities than low Earth orbits.
At 300km satellites experience significant drag and need regular boosts to maintain orbit. After collision individual objects orbit will almost always include it’s altitude at the point of impact and generally expends above and below that point. So while yes the cloud extends to higher orbit, everything would deorbit from your example extremely quickly.
Geosynchronous orbit is quite packed, but everything is moving in the same direction which prevents the kind of exponential cascade that’s so concerning. Above geosynchronous orbit’s graveyard stays clear simply because little has the energy to reach that altitude.