It is rare for Game of Thrones to leave a character behind with no conclusion to their story. It's as if the series is allergic to the idea of dangling plot threads, characters who just disappear, never to be heard from again. From Osha and Rickon to Hot Pie and Gendry, the always wraps up character arcs, no matter how big or small. This makes the lack of closure on Daario in Meereen an outlier so far. Will Daario Naharis be in Game Of Thrones Season 8? Or will the show leave him be?
In nearly any other circumstance, Daario would be a done character. He's been left to run Meereen in Daenerys' name. If he somehow manages to keep law and order in the city, he's almost certainly to disappoint the city's version of Lady Olenna, who expects a fun, debauched sparring partner, only to find a browbeaten bean counter. If he fails, Meereen turns back to the Masters, slavery returns, and much like Astapor, Daenerys' hard work and social re-engineering of the area chalks up another failure as a (now ex) ruler.
Considering viewers don't want to go back to Meereen at this late date, how Daario succeeded or failed would most likely be left to the imagination. But here's the rub: Viewers have no idea where the show will go next, and a return of Daario is as likely right now as any other outcome.
Daario could be useful when it comes to the Golden Company. This army, bought and paid for by Cersei, may not sport elephants as she'd hoped, but it gives her a massive leg up on the decimated army on its way down from Winterfell. The Dothraki were wiped out last week, as were the troops from Bear Island. The Unsullied forces have been halved. There is no Night's Watch to add to the ragtag leftovers.
The living were outnumbered by the dead in the Battle of Winterfell. But the solution to this problem, take down the head, and the body would fall, isn't going to work a second time. The Golden Company won't collapse into piles of bones if Arya stabs Cersei in the same manner.
However, Daario is a member of the Golden Company. At least, he was before he became Daenerys' bit on the side. Daario showing up with a Meereenese army, or to convince his former compatriots they're playing for the wrong team, would be a massive boon for Daenerys.
Now, to be fair, actor Michiel Huisman, who played Daario from Season 4 onward, was not seen on set. When asked in interviews refused to confirm or deny his involvement in the final season. Huisman has instead been spreading time headlining other projects, such as Netflix's The Haunting of Hill House. The chances the show would bring him back for a cameo appearance seem dim when there is so little time left.
But one might have said the same thing about Hot Pie in Season 7, and the show made room for him and his cooking one last time. With nothing to go on for next week, it's as likely to happen as anything else.