I'll harp to no end the fantasy of a progression-unlocked stations-pull-from-containers system (something set up as a parallel to the current wiring-flow mechanics, or even how Scrap Mechanic uses physical pipe attachments), and The Descent's underground POI system looks pretty fantastic from all perspectives except performance - but a new feature I'd like to see explored is some sort of a progression system for traders.
Maybe the more Buried Supplies and Fetches you do, the condition of that trader's compound improves and unlocks things- like restoring one or a couple of their broken workstations, opening access to non-craftable resources or workstations, opening access to trader inventory and/or vending machines (which I'd like to see disabled outside of trader compounds, honestly), bringing in NPCs who stay in the trader compound and offer different/unique quests, and so forth. Might be tricky to balance, but I think it's got good potential, especially if it's something that gives significant benefit without doing "too much" to minimize other aspects; easy way to do that would make harder-biome traders gain access to better things, so Rekt can't be expanded into a super-trader king of the wastelands. [Edit-add: Would it be possible to 'instance' this to parties, so the effects aren't global? Maaan, the more I think about it, this seems more difficult-to-impossible...]
On the less-development-intensive side of new-feature wants, more quest types could bring a lot of variety - especially late-tier things that would benefit from perks that lose their luster quickly, like Treasure Hunter or Lockpicking if they had something new to make them worthwhile.
