At the conclusion of Arrow's fifth season, the island of Lian Yu was blown up by Prometheus with pretty much every single supporting character still on there. That means we can expect at least a few casualties and one has now been confirmed. That is Malcolm Merlyn, the villain who has made his presence felt since the show's first season back in 2012 and even in Legends of Tomorrow this year.
"I am very sad to be leaving the Arrowverse," the actor says in the video below. "I love playing Malcolm Merlyn, and you know – that’s it really. As sad as it may be, I understand how shows must change and also characters must change and develop. But that doesn’t mean I’m not very sad and upset about it. I appreciate your support and love you all." It sounds like he didn't actually leave voluntarily then, but it's hard to say what more could be done with the character after all these years.
Whether or not this means Thea will also meet her maker remains to be seen, but it's obvious that some big changes are coming to Arrow as it enters its sixth season. We'll have to wait and see how far reaching those will be, but Malcolm's story has quite clearly reached its conclusion...for now!