Destiny had a 3 year cycle. D2 will probably do the same. D3 will then most likely have a 4 year cycle... or less likely a 2 year cycle then a D4 2 year cycle... if Bungie sticks to the 10 year plan. Destiny showed the rise of the Guardians and the beginning of the reclamation of Humanity (and Exology and... the Awokenation(?)) from the Darkness. D2, at the start, shows the fall and, most likely, rise of the Guardians and the reclamation of the Traveler. Over the course of the next 3 years, if Bungie plays this story right, would show the healing of the Traveler, starting with its salvation at the very hands of the Guardians it birthed. The first 6 year cycles will happen within our solar system. The Hive will rarely make an appearance, thank the Speaker. D3 (and if there is a D4) over the final 4 years, I posit, would be a healed Traveler and powerful Guardians taking the fight back to where this all began... the Fundament and, thus, the sisters of Oryx, Xivu Arath and Savathûn, who returned there for safety, knowledge, and strength (all information about the Hive taken from Grimoire). Or, as was originally theorized by many in the Destiny community, we are the Darkness all along. Either way, I'm in this for the long haul.