Given that 5 was supposed to launch alongside 3 and 4 and they teased a specific release year in-game, I think they’re confident about it being 2026.
As for 6 and 7, they’ve always worked on later chapters alongside whatever’s in the upcoming release (albeit at a slower pace), and Toby said that most of the team was working on 5 full-time months before 3+4 were released. I think 6 will be about halfway done by the time 5 is out. 3 being paired with 4 made sense since 3 is more filler-y, but I could see 6 and 7 being separate in late 2027 and early 2029 respectively.