So with the with the implementation of sites outside of yours that are within your holdings and the ability to exile Dwarves there to remove them from your fortress and visa versa, what would be the chance of getting "work sites" and the chance of this being done before the big wait?
By work site, I mean things like mines, logging camps, farms etc.
Starting on a site with no iron can be a real problem and require you to only outfit people with copper/bronze or painstakingly trade for iron and coal or cheese multiple sieges with traps until you can melt down Goblin weapons and armor until you have enough iron to equip the militia. When with these outside work sites, you can send Dwarves off to prospect for any type of material and they begin working a mine, sending a caravan back periodically and supplying the fortress with materials. This can extend to ores, wood, food, sand, clay and more and would help fortresses lacking in various things on the embark.
Plus with farms, you can have Dwarves run ranches etc without the issue of 30 cows damaging the FPS but you still get milk, meat and leather.
Then you have the fun of attacks on the work sites, a gold mine raided by bandits, or a Goblin faction you are at war with attacks your mine rather than your fortress, and of course, Elves upset with your logging camp send in the war grizzly's to stop the deforestation, all of which can kill and scatter your Dwarves, them returning with the tale of the attack.
Naturally this can expand adventure mode too, with them becoming randomly generated sites in history and can be formed and lost as the world progresses, and your lord could send you off to cause trouble/raze a nearby goblin mine. Plus these work sites can act as war justification/cause, "the war started over a disagreement over local resources" or some such matter.
I understand that there are plans that outside hillocks will be able to send food etc but I think having, smaller, more focused sites would also be a decent addition to fortress mode as well as the world building that benefits adventure mod.