I just finished reading the new TEW campaign, and I was disappointed with the Epilogue. After taking out Dr No, you don't want to follow him into Hell, you want to go after SPECTRE!
So here are some thoughts on a extending out the campaign (ignoring part 4) and taking out the Conspiracy as they attempt to execute their ultimate plans. I'm ignoring "Canon" history here, so FYI.
After the party defeats the Black Cowl, they are left in an Empire in turmoil. The Emperor is still ill – the Black Cowl's poison has done its damage and there is no telling if he will ever recover. Meanwhile, the Conspiracy sees its opportunity to put someone under their control on the throne.
Meanwhile, Frederick Grosz is picked up by their agents, and very willing to serve. He is not blamed for his superior's mistakes, and claims the mantle of the new Black Cowl.
The first step is to gain a majority vote with the Elector Counts. There are already some Counts under their influence (either through of greed or blackmail), but not enough for a majority. As part of that, they plan to fill the position in Averland with one of their numbers. The party must stop this from happening (perhaps supporting Graf Friedrick or Gravin Clothilde). If they are successful, the Conspiracy keeps them from taking the seat through bureaucratic stalling tactics while they consolidate power elsewhere.
Back in Altdorf, there is talk of electing a temporary Steward to rule the Empire in Karl Franz's stead – until he (ever) awakens and is fit to rule. The movement has some popularity with the nobles, but not enough to take effect. The proposed Steward is a Conspirator (or is a willing servant of the Conspiracy).
The Conspiracy needs some crisis to mobilize the remaining ECs to vote for the Steward. To this end they start planting seeds of rebellion in the populace. There are riot in major cities of the Empire. One movement has the backing of some petty lords and is able to take a capital and kill the EC (maybe Ostland, since they have recently been hit fairly hard with the assault of Chaos). Not only has the Conspiracy given the Empire a reason to desire a new leader to quell the rebellion, but they have also taken out an obstinate EC in the process. The Steward is elected. The PCs must expose his connection to the Conspiracy, prove that they are behind the
rebellion, as well as protect the Emperor from a last-ditch assassination attempt which would make the Steward the true Emperor.
I don't know, yet, how to break this into chunks that would become an adventure, but I think the structure works. I'll post some further thoughts on the nature of the Conspiracy and it's primary members.