One idea I keep returning to is a "laned" system for elevators/lifts. Two shafts for going up, and two for going down. One of the two in each direction is the "passing lane"-- and you fit dozens of elevator "cars" in the whole system. For very high altitudes it may even make sense to have a third, high-speed lane.

Obviously this would require a completely different mechanism as you can no longer have cables attaching each car to the roof. In fact I have no clue how it could work! This is what I keep pondering...