Investigate a vex portal, then we time travel. The rest of the story takes place in the Golden Age with exploration and all kinds of cool stuff, the rockets we saw on earth in destiny 1, war minds, (maybe even see the exodus black, cpt. could be our main NPC even, also big oppertunity for new enemy type. But the light hadn't been discovered yet, so we have no or limited powers (Also, tons of golden age armor and loot, golden age Khvostov would be sweet). End of the DLC, the traveler shows up, we get the light again (are the first guardians) (and a new subclass so it feels like a bigger deal), we kill main bad guy, we could even die at the same location Destiny 1 started at, and lose our ghost (who gets damaged and loses its memory of the events), so it all ties together. Raid comes in as something that followed us home through a time portal to our current time line. BOOM, Bungie, I just wrote the biggest seller you'll ever get for Destiny. You're welcome, I'll expect my check in the mail.
Sound like an interesting idea, but unfortunately for you Bungie isn't looking to hire people like you. They want idiots with retarded ideas like timers on nightfalls, and making shaders a one time consumable.