I'd like to see two new features in TS4:
1) Real Estate: The ability to buy an empty lot, build a house and then sell the home to NPCs. And I don't mean after you build the house, you just click the home and automatically sell it. I want to actually put a "For Sale" sign in the yard and have open houses. NPCs come by and you have to actually SELL the house. Give tours, dazzle them, etc. Based on your skills (charisma, selling, etc) determines how quickly you sell and the profit you make.
2) Landlord: You can build your house but instead of selling it, you have the option to rent it out to a family and be a landlord. You're responsible for making general repairs to the home (broken toilets, bathtubs) and dealing with problem tenants. Some Sims may be late with rent, some may party too much and get the cops called on them. Perhaps another family is destroying the home. You then have to go over, pound on the door and lecture/evict them.
I'd also like to see the ability to build apartments and be a landlord to multiple tenants in the same building. Be a nice challenge dealing with all the trouble Sims and keeping up on repairs and maintenance.
Also--you could own multiple lots and have several homes for rent and a few up for sale.
