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
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