I'm sure a lot of the DLC was was flushed out and well into progress when the game launched. But completed? No it most obviously wasn't or we would have Dinklebot voice overs in the Dark Below and hard mode CE would have been ready by launch not a month later. But with how often they plan to do updates you bet your ass they already had a good chunk done. Also do you have any idea what the further development costs? Server costs etc? No you don't. How much do you think the average artist makes? How much do you think their programmers make? Games this big with this long if intended support and updates cost huge amounts of money.