Bare in mind MS showed off the One before E3 in its Campus at their HQ in May 2014. I suspect we'll just seem some of that along with digital show specials on the likes of This Week on XBox. Same for SONY.
For most people, they had to stream E3 anyway. The worst part was E3 allowed consumers to play the actual games, after the briefings.
That's a bit of a loss, like E3 or not.