Your ideas are good. I'm not convinced that there will be a Destiny 2. I think DLC will win that race. With the massive amount of hardware upgrades and servers going to be at their disposal, additional content makes more sense. Halo was certainly no luck of the draw. FPS's were already around. The concept of alien race out to annihilate humanity wasn't even new. Rampant parasites? Nope. So what was it? My opinion only, Tying it all together. It was the fact that they as a whole at Bungie have a passion for gaming and an attention to detail and a great sense of adventure and a brilliant way to express it. I think you will have more moments then you can count.