more likely they were all made about the same time, and pre-planned to be released in this way so that your cousin can still buy some DLC, and many games are following a model where they release complete edition followed by 4 more DLC items or so and another complete edition or goty edition or something. its to make sure there is no one copy of the game you can buy to get it all. i say over 2012, they will release Carthage and Celts for sure and either Kongo or Zulu.
Then, they will release GRAND FINAL EDITION CIV 5 - and a month later, they will release Wonder Pack 2.
Edit --
Also, the order of continuity in which they ANNOUNCE releases has little to do with the actual order in which products are made or prepared. i stand by my idea that all of civ 5 was made up front with the idea to sell 1/3 the game up front at full price then the other 2/3 of the game in small mini-installments.
I doubt this was true of all the DLC - some of it, such as Korea, has tended to only be released in expansions in other Civ games - but there's something very incongruous about releasing the Danish as DLC when there's a Viking sequence in the intro movie. Spain was a glaring omission from the main release. And the Wonders of the Ancient World DLC must surely have been prepared or planned when the game was released - they can't have intended a Civilization release which would permanently drop three of the classical Wonders. Whether they were held over deliberately or the game reached its deadline before this content was ready is an open question.
I do however remain annoyed that there were *no* scenarios packaged with the base game, and only the Mongol one added free of charge later (and with no scenario for Babylon). Sure, the scenarios are extremely well-done and likely took a lot more time and effort to create than their equivalents in earlier Civ games, but there should have been at least a few in the standard game.
So, when the next DLC items - Celts - Carthage - Zulu and Wonder Pack 2 and 3 and Complete edition 2 and 3 come out, its all part of the plan.
Is there any reason to believe these will be the next, or even future, releases? Zulus I'd rather not see back - they have historical precedent in Civ games, but they've been quite reasonably downplayed in later versions (as expansion content or, now, apparently absent), and I'd rather the game focus on genuine civilizations rather than a tribal group led by a single charismatic - their cities are named after battlefields because the real Zulu had no cities, and they were even given a fictional leader option in one version of the game because the Zulu 'nation' didn't outlive Shaka. Adding the Malinese and, now, the Songhai in their place is more relevant thematically and more representative of African civilization.
Celts and Carthage I could do with or without - Celts again aren't a coherent civilization (then again, nor is Polynesia). But overall I'd rather see civs that have interesting scenario options and the opportunity to add new areas as maps. There already are maps for Europe, the Mediterranean and the British Isles. I've voted before to add the Merina, and quite apart from anything else a Madagascar map would be new and interesting. Several scenario options - including uniting the island or playing the French and British against one another to maintain independence in the 19th Century - would be available.
