It's been a while since we've heard anything with regards to Destiny but at GDC this year, Scott Shepard, a Technical Art Lead at Bungie, delivered a fairly extensive presentation focusing on the classes of Destiny. If you are passionate about that side of the game, and have an hour to spare, it's fascinating stuff.
Above and beyond searching for scraps on the game itself, it really is just a fascinating insight into the development of the game itself, and precisely what type of reasoning goes into the choices the team at Bungie make whilst working on a game like Destiny. The process itself is pretty fascinating, and also humbling. A lot of people put a lot of thought into every decision being made at every level.
You'll have to head to the GDC Vault site to watch, but if you have a spare minute or two, I recommend checking it out.