Microsoft has revealed their plans for this year's E3 press conference and it includes "everything from in-depth looks at previously-announced games to trailers for our unannounced titles coming in 2015 and beyond." We won't be seeing everything that have to offer at E3 though; they are saving some announcements for an entirely different event.
In their reveal for their E3 plans, Microsoft revealed that their media briefing is simply not long enough to share everything they have to offer, "This year, we have an amazing games lineup to share (who knew it’d be so hard to pack all of our exclusive E3 premieres into an hour and a half?), so we’re saving a lot of exciting reveals for gamescom in August. It’s already shaping up to be a great year."
Saying that there simply isn't enough time for their reveals probably comes from the fact that they will be showing off their AR headset during the briefing. In the beginning of April, Phil Spencer confirmed that their entire event would not solely focus on the Hololens;however, he did leave room in his confirmation that it could be a subject (and more than likely will be).
With the Xbox One supporting Windows 10 in the near future, there will also be tons of new features coming to the Xbox One in the future. These features will probably also make their way into the media briefing, an hour and a half does not sound like enough time now.
