Dead Island 2's release date has been announced at the SOLA Festival. Additionally, I have collected more detailed news about it from various sources.

┏ Source
Dead Island Official X's   / deadislandgame  
  / 1770843018251087902  
"Slaughter on the main stage: Second Dead Island 2 expansion opens up a festival of zombieslaying fun" by Dead Island Official Site
https://deadisland.com/news/slaughter...

┏ Music
"Scareobics" from Dead Island 2's Official Soundtrack by Ryan Leo Williams
   • Dead Island 2 – Official Soundtrack: ...