I'm waiting when I'll be able to store more than just 2 slaves in my house, thou it would require not only a new upgrade to the house, but also rework of slave management system in general to make it easier and faster to navigate, some kind of separate menu.
You'll see an increase from 2 to 4 slaves in the 0.8.X branch of updates. Possibly an additional set of hibernating slaves that you can fetch from some sort of "cryo chamber-ranch-prison camp-thing".
Check out our discord for progress updates, planned features, and to vote in the polls that decide what's coming next!