There is no issue with controlled and tracked satellites; we could have orders of magnitude more. The real issue is space junk, derelict satellites and collision debris. In high orbits space junk is essentially permanent pollution, which is very worrying. However, in low orbits space junk is guaranteed to fall out of the sky within a few years due to atmospheric drag. So there is no real space junk issue in low orbits, and SpaceX has modified their constellation plan to use lower orbits for this exact reason.