For one, John's younger brother was brainwashed by Damien Darhk, who has powerful magic on his side (the kind that makes even Constantine wary to tango with him). For many of the episodes this season, Andy has been imprisoned in the Arrow cave being not only a very petulant little brat, but a complete supporter of all that is evil. His older brother, John, eventually seemed to win him over bit by bit, but I think this is all an act. And last night's episode ended with the heroes basically winning (with the exception of a major character death in the leader of ARGUS), and Andy was pretty instrumental in that so now everything's forgiven, and it's all "high fives" and "fist bumps" on the way back to the Arrow cave. Only that's not how any of this works.
My Spidey sense is tingling (I know, wrong universe). I guess George R.R. Martin said it best when he told writers to "kill your darlings," and I'm thinking that's what the show is about to give us. I mean, John Diggle doesn't really serve a purpose anymore and having his own brother kill him is like another season of storylines. John used to be the "voice of reason" for the show, but that's more or less been co-opted by Felicity who was the star of Wednesday night's episode where she had to deal with all the fear and depression she incurred by not being able to walk again. In a way, Felicity and Arrow proved why they are perfect for each other and there really isn't room for John's character in the show anymore. To be honest, the cutaways to anything that have to do with John's storyline are kind of boring when compared to the greater storyline of Damien Dahrk and what's going on with Malcolm Merlyn and his army of assassins.
Of course, it could also be Felicity's mom that's in the grave, or Laurel's dad, but John Diggle being in that grave makes the most sense to me. I don't think Arrow would ever be the same after that death, kind of like the Batman was when Jason Todd (a.k.a. Robin) got killed by the Joker in the comic book four part series "A Death in the Family." That was the breaking point for the Batman, and he became "the Dark Knight" for so many years after that. And believe me, I was consuming them all because the stories were SOO dark.
So who do you think is in the grave? Are you with me or against me?