Copied save, retired fort, copied legends, and unretired fort just to see what would happen.
Not much has happened in the world since last year, except the fire imps and lion tamarin men are getting owned by goblins.
Things I noticed upon unretiring Bastiongate:
1. Everything fell out of containers. There are piles of dye and pools of alcohol on the floor everywhere. The food stockpile is full of loose prepared meals and empty bags.
2. Everything is unclaimed. Dwarves rushed to put their XX=smoke weed fiber socks=XX in the refuse pile.
3. All my captives are gone.
4. The forgotten beast is still there. Good thing I didn't put him in a cage.
5. Three tribes of cave fish men moved in.
6. Apparently I managed to get a few more galena from somewhere.
7. The units list is in a different order, both dwarves and pets.
8. All my animals are everywhere. A GDSling just killed a green devourer in the third cavern.
9. No more outpost liaison and baron, I think they moved back to the capital.
10. I'm also missing another one of my marksdwarves, I'll have to check who it was in the other save.
11. All my artifacts are unmarked except the ones being wielded at the time. I still have them all in my vault, though.
So yeah, I'm not retiring and unretiring unless I really, really have to.