As we learned earlier this month, Activision and Bungie have bigger plans for the game. As mentioned previously, the developer is planning a "major content release" for this fall, and E3 might offer us the first official details. According to IGN, Activision has confirmed that a "Destiny expansion" will be be at E3 "in some form, not necessarily playable."
It's possible that Bungie could be making an appearance at Sony's E3 press briefing seeing as how they've had a timed exclusivity deal with the platformholder, but what will be shown remains a mystery.
It's possible Bungie could briefly appear on stage to talk about the content they are planning to roll out this summer, but the spotlight of E3 seems like a better opportunity to unveil their next big thing for Destiny — whatever that may be. Earlier this month, it was discovered that Bungie had trademarked the name "The Taken King" which could have something to do with Destiny's next addition.