I basically agree with @BaseOps.
In many ways I do think the show is structurally better than it was in the last few seasons. In fact, maybe better than it's been since Vernoff left. The problem is that's not necessarily saying much given I'm not sure I care about some of the core stories & characters. Meredith is actually the least interesting character on the canvas for me. I hate the idea of losing Jessica Capshaw & Sarah Drew so that Ellen Pompeo's desire to prove she can be the central character on a show & have everyone revolve around her ( the notion of Mer as 'The Sun). And I base that on comments EP herself made... she compared herself to Viola Davis & Kerry Washington (How To Get Away With Murder, Scandal, respectively) and stated that she is just as capable of being the centre of a show & she resents that people think she can't do it. So my instinct is that's what the dismissal of JCap & Sarah Drew is about... April's presence will make folks want JApril. Arizona, despite the plane crash & being a hospital owner, just isn't well integrated within Meredith's circle.
I've come to the conclusion that had Vernoff remained with the show, we would likely never have gotten the Jackson/April pairing. She clearly never viewed them that way. Heck, a part of me wonders if, were it up to her, Sarah Drew wouldn't have been brought back... that the decision to have April be rehired & bring Drew back in Season 6 was 100% a Shonda Rhimes decision. There have been multiple times where I've had the sense that the show has been hinting at the idea of April regretting walking away from Matthew. So if they were to retcon it & try to tell us that she's come to realize that Matthew was 'The One' all along, but she just got caught up in the, I don't know... glamour of Jackson... I could see it. Matthew is the 'nice' guy next door type. The nerdy guy from high school that got overlooked. Jackson's also a decent guy, but he's kinda the captain of the football team. The BMOC. He's just so different than the type of guy she would've grown up being taught to see herself with. They're from two different worlds. Anyway, that's what I can see Vernoff thinking.
I can't help feeling that Vernoff is also a Callie/Arizona fan. Now, I know I'm a Callie/Arizona fan, so I'm biased. But she keeps throwing things into the dialogue that strongly suggest that Arizona isn't so much deeply invested in Carina or in love with Carina, so much as she just doesn't do well alone, she's lonely, and Carina's available... along the lines of "If you can't have the one you love, love the one you can have." So for me, it would be stupid to let Carina leave with Arizona. If Vernoff wanted them together, just keep Capshaw on the canvas & move their story forward. I'm not suggesting that Callie & Arizona should magically be clearly getting back together in/by the finale. I'm suggesting the show would be wise to give us the suggestion that it's on the horizon. Given how highly Sara Ramirez & Jessica Capshaw still speak of Shonda Rhimes, I still think that once a firm end date is set for Grey's, they'll be willing to come & do an episode or two that allows us to see how their characters ended up. Basically, they could have Calzona show up together & give us flashbacks to show how they reconciled.