To Eon: It was pointed out in the Diplomacy announcement 
Frankly, the multiplayer crowd for this game is tiny anyway, I don't think Diplomacy will affect it. All of you who are MP-Whores (you know who you are) will cave in and buy Dimplomacy and all will be well. As for the other 80% of the people listed as online and playing games on ICO... those people are usually friends and what not who don't pug much anyway, and they will keep doing their own thing w/ whatever versions they like.
In short... Nah, it wont make it worse, it will stay about the same, or it might even generate a few new MPlayers. But it certainly won't make things worse.
-Itharus