Arrow may have foreshadowed Oliver Queen's death in season 8 through an Easter Egg referring to a sinister group from the Green Arrow comics. It may also suggest that Oliver Queen will die a far more mundane death than what fans had theorized for 2019 Arrowverse crossover event, Crisis on Infinite Earths.
With the announcement that a 10-episode season 8 will be Arrow's last, speculation immediately began that Oliver Queen would die in the final episode. This idea was heavily built on a theory that Oliver had made a bargain with the Monitor during the Elseworlds event, offering his life in trade for those of The Flash and Supergirl. Oliver's impending death was seemingly confirmed in the most recent Arrow episodes, when Mia Smoak (the daughter of Oliver Queen and Felicity Smoak in Season 7's flashforward storyline) confirmed that she had grown up without ever knowing her father.
Given that the 10 episode order for season 8 would place the final episode of Arrow right around the time of Crisis on Infinite Earths, it has been assumed that Oliver would die as part of the event. However, episode 16 of Arrow season 7, "Star City 2040," suggested otherwise. It dropped a reference to the Eden Corps, a terrorist organization from the classic Green Arrow books responsible for Oliver Queen's original death.
Where Angels Fear To Tread was a storyline that ran from Green Arrow #96 through Green Arrow #101. The plot saw Oliver Queen (who by this point had been exposed to the world at large as Green Arrow) recruited by the NSA to infiltrate the eco-terrorist Eden Corps. Oliver uncovered proof that Eden Corps was planning to attack the city of Metropolis with a biological weapon, but he found himself on the plane containing the bomb before he could report the plot to his handlers. Left bleeding out from multiple bullet wounds while clutching a dead man's switch that would either release the bacterial agent or trigger an explosive self-destruct sequence - and with Superman unable to think of a way to stop the bomb that wouldn't kill Oliver in the process - Green Arrow chose to blow up the plane, sacrificing himself to save millions.
"Star City 2040" made mention of the Eden Corps when Dinah Drake asked her informant in the Star City Police Department who was responsible for bribing the police to fake the death of Felicity Smoak. The informant said it was the Eden Corps, who were now operating behind the scenes of a company called Galaxy One. Dinah is familiar with the group, saying they haven't been active in months. The informant agrees, saying they may be ready "to start nuking cities again." This in itself may be a nod to The Flash season 4 episode "Enter Flashtime," where Barry Allen just barely stopped the Eden Corps from detonating a nuclear bomb in Central City.
It may be a coincidence that the villains in the comics responsible for killing Green Arrow should be introduced into the Arrowverse just as Oliver Queen's death is on audiences' minds. Still, there would be a fitting resonance should Oliver Queen die saving Star City from an Eden Corps plot in Arrow season 8, given that his first mission as a hero in season 1 involved his trying (and ultimately failing) to stop Malcolm Merlyn's Undertaking from destroying the Glades. Such a sacrifice would being Arrow full circle, allowing Oliver Queen to die doing the only thing he ever truly wanted to do as a hero - save his city.