Todd Howard recently spoke with IGN (https://www.ign.com/articles/todd-howard-bethesda-fallout-5-elder-scrolls-6-starfield) about Starfield, but the discussion also included games. He talked about what Bethesda will be working on after Starfield is released. After completing Starfield, Bethesda is expected to work on The Elder Scrolls 6, but the future of Fallout has been uncertain.
Howard confirmed that “Elder Scrolls 6 is still in pre-production” and that the company will “do Fallout 5 after that.” While Fallout 4 was released in 2015, it appears that fans will have to wait at least another 5 years for the next game in the main series. Todd Howard also mentioned that Bethesda has “other projects” that the team is looking into but did not elaborate. It’s unknown if there are any plans for new IPs in progress.
Bethesda took about 7 years to develop Starfield, and with Elder Scrolls 6 now in pre-production, it will be a long time before we hear anything about Fallout 5.