Here's my problem with this issue. There's zero emotional weight to it when you consider that at some point Animal Man and Swamp Thing are going to do something that will then essentially retcon the dystopian future. Are we supposed to be shocked at the sight of all those superheros being killed? Or anybody being killed for that matter? It'll all be undone in six issues.
To me, this feels like it's supposed to be shocking in its use of dead heroes reanimated and fighting against the forces of good, but given that Blackest Night wore that concept out very quickly and not that long ago, it really fell flat.