I think it will depend on how popular that theme really was. There aren't that many different things they can do with the shops. They have already done the ice cream parlor and have done grocery, butcher, bakery, and garden stores. A chocolate or candy store would be good. A pet shop is still a possibility, but the veterinary series pretty well fills that same niche. A toy store is certainly a possibility, it's been done quite nicely as a custom by people. Hats and jewelry were done as street vendors for the Victorian theme but could make a comeback. Clothing in general doesn't really work.
What I would love to see is a further expansion of the Roman theme with some shops for that - pottery, food, togas and jewelry.