Answer:
ex-urbs resulted from suburbanization (or counterurbanization, the first term sounds better to me)
Explanation:
In the past, city planners thought about large cities as concentric rings or sectoral divisions, but the rapid growth of suburbs have challenged those concepts. As more people moved into suburbs, not only rich people, but middle class also, the suburbs gained importance. Currently in the US, more people live in the suburbs than in cities or rural areas.
This process led to the formation of small satellite suburbs that were large enough to be considered small towns, and they multiplied. Each small satellite suburb (or ex-urb) keeps growing and have the advantage of lower housing costs, and the time it takes to go the large cities is not that long anymore. I currently live on a "small town" where many people go to work in the morning and return in the afternoon. But you also notice how more and more offices are opened here, not a lot of factories though.
In my personal experience, new businesses started to form around the train and bus station, and now it is full of small bank offices, restaurants, stores and a couple of supermarkets. People who lived there moved a little farther away and it is like a small downtown area.