Too funny - I never thought of that - that I would have to wait 10 years per turn for everyone to take their turn on multiplayer. This inevitably would make CIV 5 - a long game - an impossibly long game to finish.
Well, currently there is a turn timer in online MP, there is like about one minute of time to do everything you need to do in a turn before time runs out automatically. The turn timer increases according to how many units/cities you have. So far it works pretty well, excluding the long load between each turns.
And personally I believe online MP is the future of Civ.
I'm saying this because I had the privilege of playing a FFA 6 player quick/small ancient era game that had no leavers, disconnects and crash for 3 hours until it finally ended. And I must say those 3 hours were some of the best experience I have ever had with a CIV game.
There is just no comparison between a human player and computer AI. Human players usually have no trend to predict their behaviors, and diplomacy in a 6 player FFA game plays an extremely important role. You don't want to be the top dog in the game and provoke the rest of them to gang up on you. It was extremely intense private messeging players, trying to form some kind of non-aggression or defensive pact, trying to find out which player has ill intentions towards you, which player intends to expand, etc. And when players are engaged in wars, they will private messege you back asking for assistance, and you form strategies with them involving flanks, diversions, etc.
It was just absolute pure fun. After playing that game with 5 other humans I just couldn't bring myself to play a single player game with the robotic stupid computer AI anymore.
And let's be honest here, today the trend of gaming is definitely going online competitive multiplayer. No programmed AI can ever match the unpredictability and intelligence of a living thinking mind. I seriously think that the SP heavy orientation of CIV is really dragging its potential developments and popularity amongst the more conventional and competitive RTS crowd, which proven by Starcraft 2, is a humongous population.
CIV MP will work if Firaxis actually invest their time and effort into implementing some specific system to reinforce it. For example, there can be a faster than "quick" pace setting to shorten the game.