There's two possibilities: Dead Island 2 is a next-gen PS5/Series X exclusive, or Dambuster is working on another new game.
Dead Island 2 may not release until 2021 at the earliest
Dead Island 2 PC tech review: a capable UE4 port that's smooth and stutter-free
Best Skills in Dead Island 2 - Best Skill Cards To Equip
Dead Island 2 delivers solid performance and image quality on all consoles
Who's buying Dead Island 2 day one? Or are you going to wait a little before you purchase? : r/XboxSeriesX
Dead Island 2 delayed to April 2023 as team enter final stretch of development
Dead Island 2 Speculated to Release in 2023 - Gameranx
Every Xbox Series X/S Exclusive Game Not Coming to Xbox One In 2023
Dead Island 2 co-op details (no cross-play support; supports cross-gen but XB1 players cannot host at launch) : r/xboxone
Dead Island 2 delivers solid performance and image quality on all consoles
How to Play Co-Op - Dead Island 2 Guide - IGN
Every PS5 Exclusive Game Not Coming to PS4 In 2023
Dead Island 2 - DF Tech Review - PS5 vs Xbox Series X/S vs ALL Last-Gen Consoles : r/XboxSeriesX
Dead Island 2 Xbox Series S vs. Series X vs. PS5 Comparison