Plus hopefully habitable space stations that act as immune-to-melee cities.

Some of those seem a little advanced for what they're going for, but if it's a little like Beyond Earth where you can put up sattelites to increase vision or add bonuses to certain activities then sure, I could see that. Would you need a space port to launch them?

A dedicated spaceport district would be cool, although hopefully the satellites are units or could even be armies that maybe buff each other (surveillance satellites together boosting their sight radius).

This kind of speculation is, at the moment, way out of scope for the game, which ends in the modern era, and may perhaps go as far as 20 minutes into the future.