It sounds like they're putting a lot of thought into it, moreso than the D:OS1 homestead (which was still decent, but not amazing). To me, a good stronghold evolves over the game, has a few cool events like enemy assaults and some kind of destructive event maybe, and a few quests. Maybe minigame or challenge sort of things, too, like how in Transistor, there were lots of challenges to complete in your little stronghold. They also had a music player, which would be cool in D:OS 2 (maybe as part of the shapeshifting room?) and a great tribute to Kirill. Maybe you could even meet him there, if that can be done tastefully.