Assassin's Creed Odyssey
According to Yves Guillemot, as quoted by GameSpot, there will not be a new Assassin's Creed game coming in 2019.

Ubisoft CEO Yves Guillemot delivered this news earlier at Gamescom.
"On Assassin's, we had a game [in 2018] and we have one this year, but we are not going to have a full-fledged Assassin's next year. It's just because the team were working separately, so we have two games now, one year after the other. But next year you're not going to have a fully fledged one.

Well, that just means that they're going to release a smaller Assassin's Creed game, right? Maybe they'll do some sort of a spin-off? They've done it before so it wouldn't be too crazy of an idea.

Nope. That isn't happening either.
"What you'll have is lots of content coming on [Assassin's Creed Odyssey]. The team really want to give, on a regular basis, some new possibilities for play, so when you get [Odyssey] this year, you're going to get in for a couple of years, actually."

Sounds like Assassin's Creed Odyssey is going to be a fairly meaty game once all is said and done. Speaking of which, Odyssey is slated to be released on October 5, 2018 for the PlayStation 4, Xbox One, and PC.