Like Stephen Amell said during last night, this was a mutual decision mostly because he wanted to move on after his contract expired and felt the show had run his course.
It’s sad to see the show end but i really feel like it was time for the show to end his course as the wasn’t really anything else to do with the show. The legacy of Arrow will always be the fact that it accidentally started the arrowverse as we call it. I say accidentally because it really never look like it was in the plans of the producers of the show to create this universe when it first started or even when Flash started. It just came together because all the shows were on the same network and it became something bigger.
Like somebody else wrote, this is the end of the show as it is but i’m sure if they need to use characters from the series in others show.
They’re also the rumor going around that a lot of the others arrowverse show are on the bubble after the 2019-2020 season as CW might want to cancelled most of the shows outside of Flash, which would mean the end of a era as far as the arrowverse in concern. From what i’ve read, Supergirl’s ratings went down since moving to sunday nights, Legends has been on the bubble for years now Arrow is confirm as far as being over and Flash is still holding strong but i fell the writing is on the wall for them as well mostly because they are running out of good idea to fill a season…
Anyway will see what the future hold for the arrowverse after the next crossover episode. i hope it will be good news and some of the shows will be able to get longer run but who knows.