"The way Mark Rosewater describes the development of Innistrad block, he explains that there was little confidence for his idea of a Gothic horror block, so the plan was originally for the third set to take place on a different plane entirely. But eventually it was decided to keep the setting, and just remove the horror.
But what if the creative design had been more daring, and kept the horror tone all the way to the end? Instead of threat-worsening threat-deus ex machina, what if it had ended the way the best horror movies do, with a horrifying twist?
Here's how I'd have done it: Keep the basic plotline, except Sorin plays a greater role as the one who keeps the balance between humans and vampires, so his vampire family aren't endangered, but can't overfeed on defenseless humans.
So Liliana comes to the humans and offers an alliance: they help her break open the Helvault. The humans get their angel, she kills a demon, everyone wins.
The humans condemn her, of course, because she's a witch and an abomination. But some are convinced by her insistence that they're her only hope, and together they mount an attack.
Liliana reaches the Helvault, after the humans have done their job as a tasty distraction for the monsters who guard it, and together the humans and Liliana smash it. The angels return, curses are lifted, humans are saved.
But it turns out that the angels aren't quite what the humans wanted them to be. Sorin created them with his BW philosophy in mind, not to strike back against the monsters, but to make things balanced, so make sure that humans weren't hunted to extinction. Making them fight for justice and peace wasn't on the priority list. Avacyn and her flock aren't humanity's champions. They're humanity's game wardens. And their first act is to punish those who sided with the black-magic-wielding witch with exile, as free game for the vampires.
Then the angels start laying down ground rules back home, with the intent of making sure the humans are controlled and don't fall into the hands of the vampires unless it's under their regulation. No travel unless an angel permits it. No weapons unless an angel orders you to take one up. All werewolves are either forced to live in the woods regardless of form, or become wolfir, tamed laborers for the angels. If there are not enough willing sacrifices to the vampires, the angels choose martyrs to sacrifice themselves.
The humans discover that, in ceasing to be prey, they've become livestock instead."
Mi-ar fi placut mai mult sfarsitul asta la block.(though it's still better than the RtR outcome)