The tease comes in his livestreamed Periscope Q&A session from yesterday. It is fairly non-committal, but it’s clear that Keighley is hinting at something here. As for what it may be- we don’t know yet. But Kojima has a long history of friendship with Keighley, and Metal Gear Solid V, as well as Metal gear Online 3, were all revealed at Keighley’s shows- so it’s not unreasonable to expect Kojima being there this year as well. Maybe to unveil Chapter 3 for Metal Gear Solid V?