To an extent, I think tempering expectations RE: Destiny 2 is something everyone should be doing. Not because its going to be TTK sized, but rather because whatever it is, it's not gonna fit within the traditional mold of what we consider a 'sequel'.
No matter what, Destiny is an iterative experience, and its been designed as such from its inception. They've stated in the past that their goal is to have one character you create that will be a part of whatever is 'current' in Destiny. In that sense, a Borderlands 2 style refresh of all known areas & classes just isn't going to happen with Destiny 2. However, I imagine that the content it does introduce is going to be both substantial, and something that builds upon what we already have. The most we might get is something that completely replaces the currently chain of missions/campaign/quests that is available for all starting & current players, and all of those missions are scrapped for new missions, while reusing or expanding on older environments where appropriate.
We also need to stop compartmentalizing Destiny's content scope to the amount of planets it has. We got 4 planets in Destiny 1, and the amount of content spread across them is about equivalent to the entirety of the Dreadnaught in TTK. I can already tell a lot of people are gonna likely look at the planet count in 'Destiny 2', see its smaller than what we got in Destiny 1, and call it a rip off.
