I would love to see more pets, actual pets not just stuff like the raven in life and death. Unfortunately after the poor reception of My First Pet stuff I don't think they'll make a pack with a bunch of pets again. Maybe we'll get a refresh of that pack eventually and they'll add rabbits and birds, maybe even snakes, since those already have been added but I think they'd be locked to their cages.
I'd be thrilled to be able to have more pets though, I have a tortoise in real life and it'd be cool to have one walking around my Sims yard like my little guy. Birds and reptiles are super common pets so it'd be cool to have them.