The general idea is to have to make strategic choices for empire layout (e.g. distributed,ultra-wide,wide,mixed,tall) via using policies. For ultra-wide it would be possible to get production/research/influence bonus from outposts but only for empires committed to such an ultra-wide layout. In order to enforce this policies have to be made exclusive or combine in a way that you do not have enough policy slots and you would add a well combining policy instead of a outpost boost policy if you get another free slot.
Also switching policies should be costly.
So for what kind of empires would ultra-wide be a good strategy?
For those who can not or do not want to spend the PP on colonies.
When does that happen?
- You want to expand faster because you are an expansionist empire and want to spend the PP for the fleet instead on colonies
- You do not want to hassle with side-issues of colonies: colonies are juicy targets for enemies, maybe rebellions are unlikely to happen on outposts, colonies have problems with neighbors (i.e. xenophobes)...
- You have a lot of planets where you can place outposts but no right species/tech to use these (could happen frequently to e.g. Trith or Sly empires)
- You want to expand faster e.g. in order to switch later to a tall strategy for which you need rare/good/big planets
Main balancing issues would be cost/upkeep and availability of colonies vs outposts and the other available policies/techs etc for acquiring boosts.
Cost of switching empire layouts should also be considered.
Building colonies buildings (after using a outpost part) costs currently (50+50) * (1 + 0.06 * SpeciesColoniesOwned empire = Source.Owner) * XX. As colonies cost double as much as outposts do, balancing of comparable boosts for outposts could start at half the boosts from colonies.
Flat bonus like from Nascent AI and Adaptive Automation are currently wide empire layout concepts. Keeping the values we have NAI could give +1 research and AA could give +2 industry to outposts if you adopt "outpost enterprise initiative" policy. The downsides of this is spending one policy slot and either not getting bonus from population (because you do not have a colony on the planet) or not any bonus from the policy (because you do have colony on the planet).