One more thought for the pile.
The "International" space station, i.e. the primarily US and partly Russian space station with other visitors and contributors is old and getting long in the tooth. It was intended to have been deorbited already. That didn't happen for political reasons. It really doesn't have a mission any longer, other than studying long duration space flight.
And in time, it will be brought back to earth. The ISS is far too large to allow it to reenter in one piece. Large chunks would impact the earth in a highly uncontrolled fashion with reasonably large risks to occupied cities in much of the industrialized world.
Accordingly, it has to be segmented and brought down in pieces. That is as hard to do, and as expensive as launching it was in the first place. The current configuration requires the equivalent of at least seven (or more) Soyuz capsules to provide the motive force to bring it all down. There isn't docking space for that many. That too argues strongly for segmentation.
As it is brought down, it has to now run the gauntlet of the SpaceX low orbital fleet. But, the pieces of the ISS are not spacecraft themselves and they will have extremely limited maneuvering capability. The SpaceX fleet will have to get out of the way!
That raises a very serious question. On earth, priority is given to the older things that came first. Pedestrians over horse and bicycles over cars and lorries over other things. Trains were made an exception to this. They are so massive that stopping on a whim is not an option.
Sail craft have dominance over vehicle traffic on bridges, and over powered boats, ... And again, the behemoths run by different rules.
So too in space there will have to be a precedence order on who must move and who must yield right of way. Likely that will mean that smaller maneuverable craft will be required to yield. Larger craft and of course - out of control craft get right of way. And as now happens with aircraft travel, even one plane being forced to divert has a cascading effect on others requiring intense air traffic control issues.
If that doesn't happen, or if SpaceX has not programmed in that reserve and ability, then collusions become much more likely.
If the US, the Russians, the Chinese, the Indians, or anyone else decides to put a space station in orbit, the same rules will likely apply, both for orbital ascent and for deorbital descent. In time, they will all want to have their own station in orbit, if for no other than political reasons. Then too, their will no doubt be a mad rush to the moon and beyond.
That then leads to yet further concerns and questions.
Consider what happens if a new war in the middle east breaks out and turns hot. The chances are good that that escalates into the destruction of the oil terminals in Saudi, Oman, UAE, Iraq and Iran as various sides employ asymmetrical warfare to offset imbalances in other areas. Instantly the world is in an extreme energy crisis. Equally quickly companies and governments fail. War escalates. Ships are sunk in the gulf rendering passage difficult if not impossible - prolonging the lack of oil.
From the climate end of things this is good. From the human end of things in the near term this is catastrophic. Over the long term it is somewhat better, though the elimination of the gulf oil from world stocks is not in itself enough to turn the tide on climate destruction.
And then there is the sky.
As companies and countries go bankrupt and turn their attentions to war of various types, the resources to maintain the satellite fleets falter. SpaceX being one of the newest is most economically vulnerable. And like Iridium before it, SpaceX could go bankrupt leaving the SpaceX fleet as an orbital debris field. But who has the controls? Who has the codes to order the craft to maneuver them, or to deorbit them? Do they even have enough fuel reserves to do a controlled re-entry? They are not after all full blown space craft. They are simple satellites with ion thrusters.
Etc...
The movie Gravity that Neven referenced now becomes prologue to the real event. Unlike in the movie, there won't be any hopscotching between space stations. It will just be one big battlefield of debris, with Astronauts, Cosmonauts and Tychonauts hoping they can navigate their return craft through them safely to earth.
Sam