In 2016, before The Elder Scrolls 6 was formally announced at E3 2018, Todd Howard confirmed that Bethesda was working on a new Elder Scrolls game (because of course it was), but warned that it was an extremely long ways away: So far off, in fact, that he implied the technology required to make it happen didn't actually exist.
"I have to be careful what I say—it's a very long way off," Howard said at the time. "I could sit here and explain the game to you, and you would say, 'That sounds like you don't even have the technology—how long is that going to take?' And so it's something that's going to take a lot of time, what we have in mind for that game."
Five years down the road and three years after the announcement at E3 2018, it appears that the situation may not have changed as much as you might have expected, or hoped. In a new interview with The Telegraph, Howard said Bethesda is still working on the technology that The Elder Scrolls 6 will demand.
"It's good to think of The Elder Scrolls 6 as still being in a design [phase]," Howard said. "But we're checking the tech: 'Is this going to handle the things we want to do in that game?' Every game will have some new suites of technology so Elder Scrolls 6 will have some additions on to Creation Engine 2 that that game is going to require."
The Creation Engine 2 will first be seen in Bethesda's upcoming sci-fi RPG Starfield, and Howard warned—again—that Bethesda is all-in on that game right now. The development projects "kind of intertwine," he said, but "the vast majority of our development development work is on Starfield right now."
Starfield is currently expected to be out in November 2022, and The Elder Scrolls 6 will come sometime after that. At the very least a couple of years after, would be my guess: Bethesda's Pete Hines said in May 2020 that it would be "years" from that date before details of the new Elder Scrolls will be revealed.