The story is the beginning of the game. It's basically the intro to the world etc. The story starts at lv1 and makes sense to end at lv20 which is the first level cap, and also when the real game begins. After which, you begin your journey to reach the actual current level cap of lv30 which I assume will be where the vanilla version of the game ends. (levels after 20 are granted from acquiring gear with motes of light on them) And requires hard mode raid gear to achieve (which will take a long time to achieve.) And next they have already said the first DLC should be around December. Which who knows what will happen then, but the next dlc will come soon after that also. And so on and so forth. Basically. There should be a steady flow of things to do assuming you don't mega power grind and skip everything to be world first lv 30 or something.