The Benandanti will most likely have no way to deal with the Shroud, for better or worse. Same with the Arcanum, though some of their more learned members might be able to find some obscure prophecy that foretells what is about to happen, and send others to locate something that could help stave it off. Given their track record, however, it's more than likely they'll just make things worse through their shockingly-incompetent meddling.

As for the Orphic Circle: we have one of their members to thank for the 6th Great Maelstrom, and most of their membership perished when something happened at their headquarters. The remnants don't seem able to do more than stumble through their lives or hide in total fear, which doesn't make for a great calling up of the troops.

It's still possible that some of their more powerful members could escape these problems and take a more proactive role. But considering that the Orphics delighted in activities that weakened the Shroud that might not be the best thing. On the other hand, some of them may have spent all this time trying to find a way to undo the damage they feel they're responsible for, and now could be the perfect moment to let it loose.

{For more details - and a lot of questions - on what happened to the Orphic Circle after Ends of Empire, see Hunter: First Contact }

There is also a chance that the Inquisition could play a deciding role. Faith is a strong weapon against beings from the Shadowlands, and one could decide that it could pose a barrier against Oblivion, itself, as well. If the Inquisition were to uncover what is about to happen, they could try to convince certain elements within the Vatican of the approaching threat. Millions of Catholics all over the world could then be instructed to pray for deliverance, and maybe - just maybe - the Shroud could be strengthened enough to hold back the darkness.

On the other hand, maybe they'd decide that this is Judgment Day, and all they'd do is tell the faithful to prepare for the end. The global prayers will actually weaken the Shroud via increased belief in the supernatural, and whatever would have happened will be that much worse for the interference.