Ok, recently I got to messing around with fallout shelter. I find the game fairly addictive. And got to thinking what bits about it I like the most.

Sending out wanderers to get supplies. - Modding that should be simple. You could either:

1) Send the person out in the wasteland, and roll some dice in the background every now and then on what they find, or what attacks them

2) Send the person into a cell outside the game (where nobody can attack them), roll some dice much like option one. The added benefit is you have more control on what happens to your npc

Personally I am of the opinion of option one. Have a script that picks a random path for your npc, as he/she follows it random encounters in the world will happen. Have another script where your explorer loots up any dead bodies, and continues on his merry way. It would give you great incentive to load your explorer up with lots of stims, rad-away and guns.

Building downwards:

Settlements are nice, but a vault would be neater. In theory it should be possible. You would need to create a unique set of materials, for the walls, and the vault door would zone you into your new cell.

Jobs:

From what I understand, the settlements already has some of these features, but it will likely need to be expanded. Like a job of a higher level npc to train lower level ones. Or rooms that increase npcs special stats. Or a nuclear reactor where if you mistreat it, it might convert some workers into ghouls.

Building an underground vault might be more tricky than building on a plot of land in the overworld, but there may be a few ways to get it working. Easiest would be to just make a vault with a ton of empty and unlighted rooms, and let our player furnish them to their specifications.

As for sending settlers to explore the wastes, that would be awesome, but I'm wondering if the AI will keep going after they get far enough away from the player that they're not loaded into memory any more. Otherwise, it would be trivial to set up a Radiant AI package that tells them to go to a certain location and loot freely along the way.

And honestly, being able to Ghoulify our settlers through negligence (or deliberate sabotage) would be badass. If we're just going to get generic and random settler NPCs, I want to be able to do whatever I want to them. (although unique settlers I can understand having more protections, and more limited roles)

I think he's talking about ideas from Fallout Shelter he'd like to see incorporated into the settlement building mechanics in Fallout 4.

He is, I wonder if that will be a settlement option. Im sure BGS has thought about making a vault a settlement area. Eight weeks to find out.