Rob Daviau from Hasbro Games recently responded to a post on Usenets inquiring about a Lord of the Rings RISK expansion pack. This is what he had to say:

“Sorry to disappoint you but it will NOT be a two-player expansion.
The new game will replace the game on shelf. It will have two more panels to the game to incorporate Gondor and Mordor. It will have a third deck of territory/adventure cards. It has a totally rewritten rulebook. It has new rules for “Alliance Play” and “Team Play”. It cleans up confusion on the cards. It clarifies rules in the game. It contains more pieces to account for the larger number of spaces.

The only thing I have not been able to do is figure out to get just
the pieces you need if you already own the first version. Unfortunately, you would need:
The new board
The new rulebook
The third card deck
All the pieces again (since they are bagged in one bag, we can’t just send the extras)

Then I realized that you need the first two card decks since the copy has been clarified and modified. Then I realized that the card backs will be blue, not red, so you need all three decks. (The blue is keeping with the ROTK style guide and to ensure that the correct decks are put in the game on the assembly line.)

I also realized that the vacuum-formed tray is different to account
for the larger number of pieces and cards.

So the only thing that carries over is the ring and the dice. Everything else is significantly new.

So it is a re-release. On shelf in December.”