This may be considered a spoilery post as I'm going to connect the dots on who is likely to have survived Lian Yu at the end of Arrow season 5 as well as cover who is likely the big bad for season 6. If you are behind on the show or would rather start the new season fresh, then you're probably going to want to go away.
Starting with who survives the explosions on the island. It was a pretty save bet that Wild Dog, Black Canary and Black Siren were going to survive as Rick Gonzalez and Juliana Harkavy were named series regulars for season 6 and Katie Cassidy is back as a recurring character. Then the other day we got the official look at Harkavy in the Black Canary costume, and that solidified that.
And then there was 'loose-lipped' Stephen Amell who told fans at a convention: "I can report that Manu Bennett is back to being a part of the show and I think we will see him multiple times this year, which is awesome." He also teased a character who hasn't been seen since season 1… which may or may not tie into the villain for the season. Or it could be the house keeper, Raisa.
Which leaves the following characters in question: Curtis / Mr. Terrific, Quentin Lance, Felicity Smoak, Thea Queen, John Diggle, Nyssa, Talia and Samantha. Now I believe Quentin will be playing part of the Black Siren storyline, so he seems safe. As for the others.. I doubt they'd kill Felicity, Diggle or Thea… but you never know.
Now on to the bad guy. A casting announcement went out for the show:
[Ricardo Diaz] Male, 30s-40s, Diverse. Hardened ex-son recently released from prison for crimes he didn't commit. Ricardo uses his freedom and 25 million dollars in settlement money to establish control over Star City's criminal underworld. He's a martial arts and fighting expert honed by years of life on the street and in prison. 7/13 Fractional Series Regular.
Ricardo Diaz is of course the DC Rebirth version of Richard Dragon… or rather the son of Richard Dragon. This is a character that has seemed perfect for the series as he puts together a team called the Long Bow Hunters which included Clock King, Brick, Count Vertigo, Red Dart and Killer Moth. Three of those five are already in the Arrowverse and the could easily replace one of the other two with Cupid.
This casting call hasn't been verified by the CW or Warner Bros Television, but it is very simliar to the call that went out last year for Tina Bolland who turned out to be Dinah Drake.