Recently, foreign media outlet Tech4Gamers reported that Bruce Nesmith, a former Bethesda developer who worked on Fallout 4, shared his thoughts on the setting for Fallout 5 in an interview. He believes that setting the game in London or Paris would deliver a stunning experience.
The mainline Fallout series has historically been set almost entirely within the United States. Moving beyond the U.S. would mark a significant stylistic shift for the series and could attract a new player base. Nesmith stated that future entries in the series need not be confined to the United States. Even if the setting remains within the U.S., choosing unique mid-to-small-sized regions like the Grand Canyon could still align well with Fallout's post-apocalyptic theme and artistic atmosphere.
Bethesda has confirmed that Fallout 5 and several other IP spin-off projects are in planning, but the company has not yet released any official information regarding the story background or location. The aforementioned ideas are merely the personal speculation of this former developer and do not represent the actual direction of official development.