Lanni/GJ alliance (Spoilers All)

If you are not up to date on the books or show and don't want to know spoilers, then I would recommend not reading the rest of the post.

In the 2nd edition board game, an alliance between Lannister and Greyjoy can be very dangerous. If they both can successful can withhold from backstabbing the other early on, it's likely one of them ends up winning (GJ more times than not). So given the progression of the show and the new potential alliance between Cersei and Euron, I don't think the rest of Westeros has any clue of what could come from this. While it's likely that Euron is playing Cersei or vice versa, if they can manage to work together (like in the board game) then things will become grim real fast for everyone else.

What do you guys think?