So after learning, a lot, from the Mod Jam, I'm going to use some of that with SIHO. So far some of the initial ideas I'm thinking of including, in order of priority;

1 - Updating the modifier that habitats give colonies. Anyone whose tried out my origin on the Mod Jam would know that it includes a building which gives scaling bonuses to a planet based off of the habitat's districts. A similar system will be used but through a planetary deposit on the planet made when the habitat is constructed. The bonuses won't be as strong as the ones from the Origin, but the Space Elevator from the origin will instead double the bonuses provided by that deposit when/if I integrate Stellar Pioneers into SIHO. So instead of just 10% trade value bonus (sorry gestalts!) you can get your colony beneath a habitat to have things such as mineral production output, a smaller all resource output, amenities and immigration attraction, or yes trade value. There should be alternatives for hive minds and robots now too, as well as bonuses for energy and mineral districts, in case a moon unlocks that habitat type (or you're playing gestalts who have energy districts always).

In addition, once 2.10 comes out, I'll have habitats give the +1 job per district from the respective energy/mineral/food hubs to their planet as well as the resource output. It makes a lot of sense to me that off loading additional processing to a colony's habitat would have similar bonuses, and reinforce the role of habitats supplementing a planet's industry. Besides, habitats are getting a pseudo nerf for resource production because they're going from 50% better to ~33% better with the hub increases.

2 - Experimenting with giving habitats bonuses contextual to the colony they're on. This one is very tentative, because while its a trivial matter to scope from a planet to its moons, its near impossible for a non-fleet or megastructure to scope from its moon to its primary (and yes, while habitats are listed as a megastructure, they change in type from megastructure to planet when you finish construction, so that doesn't work either). I'll be experimenting with event_targets or euclidean distance limits to see if there's a work around, but it may be a bit messy and processor heavy, and thus need to be dropped.

3 - Adding a miner and technician building to respective habitats, equivalent to the hydroponics building (which will be increased by the +1 job output of hubs, MAYBE +1 for Void Dwellers as well). Habitats in 2.10 will apparently have a lot of buildings compared to districts, and this will help them continue to scale for base resources once their districts are built. Some concerns that it may be a bit too potent with the ~30% resource bonus you can get from your starting system's mineral outputs (but that's, what, 1.5 technology upgrades - 3 if you're playing with Stefan's? :P).

4 - 'Fortress Habitats' protecting the colonies beneath them. If I could make it work, and make the AI able to play around it as well, the idea that you need to take a habitat before you can invade the planet beneath it is quite flavorful to me. Think of the opening of Halo 2 where the Covenant needed to take down the SMAC stations, or Starcraft 1 where you needed to take the orbital installations before landing on the planet. As a trade off, it would be an awful shame if the enemy just... bombarded your habitat until it became an unlivable ruin. Those armor technologies might be able to make your habitats a tougher nut to crack though, and those shield generator buildings might get some use finally.

5 - Capital Habitat planetary designation - thinking of adjusting the current +10% trade/unity bonus a capital habitat gives to instead be its own type of colony designation, providing similar benefits that your capital has. I mean, it basically is apart of your capital after all... right? :P

6 - Events! This is the main thing I learned from the mod jam, and I've had a few ideas in mind for a while, but couldn't get my head around the event system (curse you planetary events not having multiple options!). Including the hinted ability to bombard habitats into dust rather than invading them, some involve the 'special worlds' throughout the galaxy. Events dealing with relationships with the Spiritualist Fallen Empire if you build a habitat above their holy world (and perhaps dedicating that habitat to trading with their pilgrims), habitats above your own holy worlds if you take the Consecrated Worlds civic and bonuses from there, special districts for the dragon's hoard?

Ultimately there's a lot of ideas to add more events to habitats that ultimately miss out, not having any colonial events of their own. It probably wouldn't make sense to give them events as often as a planet's colonial events, but spicing some here and there could give your habitats a bit more flavor than just 'energy hab 1, miner hab 3, etc'. One I might salvage from my earlier attempt is an event which moves your capital from your planet to your habitat above it once its sufficiently developed, giving a reduction to Empire sprawl as your administration focuses on a truly space aged Empire, or you can tell those pesky hab dwellers that your homeworld will always come first, for a happiness bonus to dirt dwellers and a penalty to hab dwellers.