In my honest opinion i Believe Fallout 4 takes place in San Francisco Go to Youtube type in Fallout 4 Official trailer then find a video named Fallout: 4 San Francisco - Official Trailer and Give me your opinion and dissagreements and other ideas where you find my information is wrong and think it takes place elsewhere.

Bethesda hasn't announced any future titles. That video was made by a fan, it is in no way official, I'm afraid you've been trolled.

If you want to discuss locations and settings for future Fallout games please use http://www.gamesas.com/topic/1385211-official-future-fallout-locations-suggestions-topic-16/.