Todd Howard has recently confirmed that Bethesda is looking to use and further modify Creation Engine for games coming after Fallout 76. This sets a disturbing precedent, as this means TES 6 and Starfield will use an outdated engine.
Impressions and early reviews are coming in for Fallout 76 already and they are mixed, at best, with many negative reviews happening due to Creation Engine issues. Players are reporting performance issues, outdated textures and that are not really justified by what the game has to offer.
To be fair to Bethesda, all of these issues were reported in Beta period, and the company even issued an that basically asked players to be patient with Fallout 76. They do mention in that letter that they are constantly finding new ways to push the Creation Engine, but that's nothing modders haven't done before really.
Yet, in an with the German gaming site, GameStar, Todd Howard implied Bethesda will keep using Creation Engine for games after Fallout 76. He talked how Fallout 76 has a new way of rendering and a new lighting system, while for "Starfield even more of it changes" hinting the title will indeed be made on Creation Engine. Howard continued by saying there will be even more changes in The Elder Scrolls VI, meaning the engine would be further utilized.
Considering that The Elder Scrolls VI and Starfield are still months, or likely years, away since we didn't see any gameplay trailers yet, it is quite possible that Creation Engine's flaws will be even more visible then. With games such as Cyberpunk 2077 likely releasing in a similar time window, seeking to push the gaming standards further, it's safe to say it will hurt to even try playing titles made on an outdated engine.
Since even Bethesda don't seem to know what Fallout 76 is, many fans assumed the game was a placeholder while the company built a new engine, but this doesn't seem to be the case. The interview with GameStar is from June 2018, meaning the new titles are likely already in development on Creation Engine.