Answer:
The best replacement for the word deracinated in the sentence is cut-off.
Explanation:
The definition of deracinate is to tear something up by the roots, the sentence presents the example of a regular neighborhood where people are close to each other and there's a feeling of belonging, people have roots in there, on the other hand, social networking is not land for anyone, people don't have roots and are just "deracinated" or "cut-off" kind of people.