I wrote this before but I belive we get Civ announcement this year:
2K Games has written that there will be several Firaxis projects announced this year, including new franchise in August. That game was Midnight Suns.
Now we are supposed to have Civilization 30yrs anniversary specials and surprises so I think announcement of a new Civ would fit there quite nice, with release sometime in 2022.
When a civ edition is released, it takes somewhere around 5 or 6 years for the next edition to be released. Civ6 was released in 2016, so a release in 2022 sounds very likely. However, as much as I want and would love an announcement this year, I don't believe it will happen, it's just been a very short time since the last DLC release. That said, I believe in an announcement in the first half of next year and the release in the second half.