Does Stephen Amell's Oliver Queen have a future after the eighth and final season of Arrow? The answer to this question is unclear, but it is possible that the Emerald Archer's story can continue, even if he no longer has his own series. The Green Arrow can basically become the Arrowverse's version of Hulk in the Marvel Cinematic Universe.
The flashforwards throughout season 7 of Arrow heavily hinted at an early demise for the hero who started the Arrowverse. The season 7 finale confirmed Oliver's death with a tombstone. Exactly how Green Arrow's story will end remains unclear, but the Monitor dropped a clue when he told Oliver that he was destined to die in order to save the universe, so his mission is expected to be essential to the plot of the upcoming Arrowverse crossover event, "Crisis on Infinite Earths".
While all signs are pointing toward Oliver dying in "Crisis on Infinite Earths", this may not necessarily be the case since Stephen Amell says he's open to returning as Oliver Queen after Arrow is over. Arrow will end after season 8, but the Arrowverse will live on with The Flash, Legends of Tomorrow, Supergirl, Batwoman, and a new Arrowverse series confirmed for 2020. Though Oliver still maintains connections to characters on The Flash and Legends of Tomorrow, a guest appearance on any Arrowverse TV show still seems like a strong possibility. If Arrow's ending includes a twist that somehow doesn't kill off Oliver, a return could happen.
If this is the future for Amell's character, it sounds a lot like Marvel's approach to Hulk in the MCU. The Hulk hasn't had a solo film since he was portrayed by Edward Norton in The Incredible Hulk. Due to rights issues with Universal Studios, Hulk can't headline his own movie anymore. But, that hasn't stopped Marvel Studios from getting plenty of use out of the character. Despite not starring in his own movie since 2008, the Hulk has teamed up with other heroes in four Avengers movies and Thor: Ragnarok.
The Arrowverse can follow a similar formula for Oliver Queen after Arrow season 8. As the Hulk has proved in movies like The Avengers and Thor: Ragnarok, an iconic character doesn't need a solo movie or a show to get their chance to shine. By January 2020, Arrow will have had eight seasons to tell stories about Oliver Queen. Though his story may be coming to a close, he can still take part in the stories of other heroes, like the Flash. He could even show up for the 2020 Arrowverse crossover.