I'm sure we'll live. E3 hasn't been any fun since they got rid of the booth babes and started their "games are serious business" crusade. Most big companies now have their own events anyway and as a PC gamer there has been very little to take away from a mostly console-centric E3 in the past few years. It had become a very stale and boring event in my opinion.
They can still reveal games and have live streams to make up for the cancellation. It might even get better and spur creativity compared to a live reveal on stage.