Rio de Janeiro
You'd still need tiles with numbers on them.
Yes, but that could be easily adapted. Most tiles with numbers are the ones that have only roads. You could have small numbered tokens that would be randomly drawn whenever a roads-only tile is placed, for example. Not as elegant, but certainly less annoying than having to buy the whole game again for what is indeed a mini-expansion. But if that marketing scheme worked so well for Dominion, why not do the same with Carcassonne?