Here's a few more while I'm in this thread:
1. Italy has the ability to form the Roman Empire if they conquer Turkey and North Africa.
2. Mechs as a late-war technology.
3. Time-travel assassinations.
4. Sunset Invasion Part 2 DLC, Mexico has a 0.1% chance of spawning with thousands of tank divisions when a game is first loaded.
5. Optional method of winning a battle by each side putting their commander in a boxing ring.
So Dieselpunk vikings?
That'd make for an even better april fools.
Just once I wish PDS would release one of their April Fools DLCs as an actual product; I would pay upwards of $20 for the CK2 Cat DLC.