So I just saw the event, it was good, a lot of games and announcements.
But for the moment I stay team real, due to the following reasons:
1. There are so many unexplainable things, coincidences about the whole thing.
2. We knew already that Kojima loves to troll people and did it again by intentionally make it seem like he would appear at the event.
Well I have to accept that I misread / misjudged the tweet. The tweet should have been already a confirmation that he will not be at the event, because if he would be there, he would have surely kept it a surprise and don't post so obvious tweets.
3. At this showcase there was nearly no talking so it would be odd if he suddenly shows up and talks, since no other developer was talking also and just showing that Silent Hills is real and Abandoned was just a cover in a trailer seems a little bit strange
4. Kojima is a Japanese developer, so its possible he save the announcement for a Japanese event.