I remember when it was said "DB makes too much money not to continue the following year (2019)" but now it's "DB makes enough money that it doesn't need to continue for a few years". The new Demon Slayer film is now the highest grossing anime of all time worldwide and grossed almost 3 times as much as Broly but the studio is still working on the second season to adapt the rest of the manga.
I think Toei is taking their time because they want to avoid what happened with the first DBS anime. Aside from pre-production issues, there isn't much source material to work with. It might be easier to wait for the manga to get ahead enough or end and use that as an outline rather than just the short written outline from Toriyama. If the anime returns after Digimon ends this year, they would catch up to the manga in less than a year while it's probably still on the Granola arc. If nothing is announced this year, I think the earliest would be 2022 or 2023 depending how long the anime replacing Digimon will last. That would give the manga enough time to complete the Granola arc.