I'm betting they don't give a fuck. I'm only going off of scene snippets from a the 'Everything Wrong With' vid, but Barret apparently gets killed by Sephiroth in Shinra Tower - as in actually impaled and pronounced dead in a cutscene - and the Whispers just bring 'im right back. So complete nullification of the impact of character death notwithstanding, when it comes time for Aerith to get her big dramatic death, I predict one of two things is going to happen: she's either going to live, because this is the new reality where everyone's happy and nobody really dies or...Sephy and sword start descending on her in slo-mo, Aerith looks up and sees the Whispers, who slowly and dramatically shake their heads, and Aerith nods stoically, accepting her sealed fate as Sephy runs her through. And I am going to laugh my silly ass off at either outcome, which is the very last reaction I should be having over that scene.
Those Whispers are dead by the end. So death is still a real threat. And I'm glad because I thought the whole Whisper stuff was dumb. But I liked the other added story content. ---