I like the idea of the Borg reality from "Parallels" because it is absolutely the end. Not even that, it is the post mortem of the end. The likely POD is the Borg succeeding in their incursion of Earth in "The Best Of Both Worlds", and no one figuring out a way to stop them. That seems the intended POD of the other Riker reality(ies? I don't recall) in that episode, though never explicitly stated. They have lost, and everything is over. There is no redeeming it. There is no saving the day. Everything is gone and ruined. Everything personal these characters know has been ripped away from them. There is nothing that can be done except to try to live one more day, and to suffer constantly, knowing all the while that at some point you will all be assimilated or destroyed because you are living after the end. And there is no mcguffin to turn that around. It is a universe of ruin and misery that will only get worse and never better.
That all hits you in a matter of minutes, seeing what things have become and what Riker has become. He's a crazed man on a bridge empty only for him and an equally disheveled Worf in the background. He has a thousand yard stare, and barks like a madman, with no sense of civility and regulation, only with an interest in survival or suicide. It plants all kinds of ideas of what he has seen, suffered through, and lost which, while never defined in detail, must have been horrific beyond imagination. And the worst part is that all of the ups and downs, and all of the Michael Pillar human moments of seasons 1, 2 and 3 up to that point all go the same, before everything goes wrong.
