In recent news, a recent post on the website called Reddit as a user named "Fallout4Boston" said that the next game in the Fallout series will take place in the area of Boston, Massachusetts. In the fallout world it is called the Commonwealth and has been surviving with building tech and inventions. Betheseda has been recently researching and scoping out Boston and they are really close to MIT. The last update for the domain of Fallout 4 was on May 7th of this year. The user did not want to say anything else to possibly losing their job. This could be true with The last game Fallout 3 taking place on the East Coast also. this just could be a rumor but if it isnt it could be soon announced in the coming monthss or at VGA Here is the link to the post on Reddit if you want to see it. 
Here's a link to a article about the rumor.