I like this ending, but only if it's not a real one.
To build a good tragicomedy, which it would be at this point, you need to watch out for not loosing consistency. And as much as i like this show, now it is everything but consistent in tone, and mood. Thought it seems to be getting better, and better at it (and absolutely not only at it). Clearly it was going to be something else at the beginning, and it staggers the evolution a bit. Still distance past is impressive.
It can be a great rising the stakes but as a real ending I feel it would be rather cheap trick used for a shock value. I really hope that they will wrap this up in the next episodes / season. Not necessarily with happy ending, although it would seem most appropriate, but showing closing of character arcs.
PS: Looking at all of this, our reaction for the episode is exactly what creators intended. There is nothing here that REALLY is saying that the series is over. It seems a tale of the end, not the end of a tale.