Don't worry greater Paris like the Paris would have arrondissements.
But too many municipalities are very difficult for planned big projects.
Exemple the Metropherique (Circular metro line in inner suburbs) should me more easy to built if it would be in one city, but today it is more than 20 city for 40 station :nuts:
This line is very important 1 million passengers per day are planned it would derserve important business district (Val de Seine, La Defense Levallois, Plaine Saint Denis...)
The area of greater Paris has 137 municipalities for only 6.7 million inhabitants and 723 kmĀ²