It's definitely not going to be open worlds or a color wheel. Especially open worlds. They have said multiple times that it's not possible. The game would have to be built for it at the base. The engine is not designed for open world. The closest we will ever get are larger neighborhood areas.
As for a color wheel, cats and dogs was specifically built with it from conception and it only affects pet coats. The base game was not made for it and it can't be put in at this point.
I do, however, think there's still hope for some kind of personality system, even if it overlays the current one. They could feasibly do a trait tree like Vampires have, but for "normal" traits, like preferences. I'm hoping we get something akin to that because we definitely need some kind of personality and behavioral mechanics to make Sims unique.
