If they really don't want to go with a EP for Zombies and specially Haiti, since all the supposedly difficulties about giving us unpopular features and a full african world for free/paying (i know Haiti isn't in Africa, but you know...) i'd like to see them back as an event or game challenge for base game.
For gameplay we could get something like the Vampires Nexus lot trait or the Scare Seeker lot challenge, where Zombies spawn every night but only attack sims and doors/windows (NOT PLANTS) at full/new moons.
For zombies appearence the team could use the old Grim Reaper's skin, the sleepy walkstyle but a bit slower, and swatches for dirty (like the ones form Horse Ranch) and ragged clothes. Give us a new voice and make it a new full life state. They could loose all their traits and skills at first, and spend more time to raise them, failing more and to get a personality. Their needs could also be harder to fulfill
- Loose all skills: They should learn the child skills first or at the same time (Creativity, Motor, Social, Mental).
- Basic interactions are "Arghhhh" and "Brains!": As they learn social and mental skill they can elaborate more normal interactions. I think it would be funny if the interactions were written like "fRiEnDlY iNtRoDuCtIoN"
- Dance to the songs: Building up motor skill allows them to dance more perfectly.