If reports from the Metal Gear 25th Anniversary event are accurate, it looks like the most recent MGS news could be the biggest. According to attendees, Metal Gear Solid: Ground Zeroes is the next in the series, runs on the new Fox Engine, and may be an open world game.
Famitsu.com reports that Metal Gear Solid: Ground Zeroes is the name of a real-time demo shown by Kojima Productions, which is also being turned into an open world game aimed at the current generation. Here's the first piece of artwork:
What do you think about the possibilities of an open-world MGS?