I can't wait until there is mass migration and "retire fortress".
Yes! The one feature I would most like to see added (to Fortress Mode) is the ability to take some of your resources and animals (hopefully keeping intact the
genetic traits inherited from breeding) from your old Fortress, along with seven dwarves, to embark towards establishing a new Fort.
This would put a whole new spin on the term "succession game". (I'm thinking "Succession Embark" might be more appropriate.)
What I mean is that the player would effectively give up control of their old fortress. This would be similar to Abandoning their fort, except that NPC dwarves (or whatever race, via a mod, the player was playing as) would still inhabit it. Then it could be more fun to revisit the place in Adventure Mode, esp. if your exotic pets are still there...
Also, this would be different from the usual Embark method in several ways. Before leaving the old fort, the player chooses which dwarves embark with and which resources and animals to take along. But as before, the player is restricted in terms of points to spend (determined by the item and pet value). Also, skills could not be bought because it's assumed that your dwarves are already skilled.
Being allowed to bring along stuff from the previous fortress would allow for certain animals and goods that are normally not possible on Embark. Yes, I realize that there is some potential for such a system to be abused. But the points available limits that. And if the player wants a challenge they would try to limit what they bring. Anyway, I do wonder if this
might make for slightly easier settlement of difficult biomes and climates, such as Evil or on Glaciers.