At a time far in the future, humanity has long expanded past Earth into nearby planets and solar systems. The planet in question was heavily used for it's resources to supply other planets who's resources were beginning to run out. Eventually, conversationalists heard of it's existence and protested the abuse of the planet and it's life forms and, consequentially, it was abandoned soon after. Years later, the interplanetary government decides upon a different way to use the planet.
The planet is hollowed out as best as can be without coming too close to the core or too close for the machines needed to melt. To replace the massive amounts of resources taken, it's replaced with technology. Eventually the massive internal cavern has transformed into a futuristic hub of activity, known for both fair trade and corruption. The living structures resemble stalactites, spiking from both the bottom and top of the cavern. For reference, It looks somewhat similar to civilization in the Altered Carbon series.
I originally planned for the planet to be completely split in half in order for it to be accessible from the outside, but I believe simply hollowing it out and leaving few ports of entry with high security is a better option.
My question is: Is a sustainable colony possible in a hollowed planet like mine? How would life there be any different than life on the outside of a planet?
Science and logic based answers please, I'd like this to be as realistic as possible.