My guesses:
1. Games will have been replaced by a new entertainment medium so advanced that games will only be played as a form of sociolgical research similar to how old documents are read now.
Game most played: GTA 4
2. Games will have elvoved into a work of art that inspires emotions so powerfull that people will be brought to tears. In this today's games will be played so as to be seen as having timless artistic depth that renders graphics irrelveant.
Game most played: Probabley some arty indie game like Passage, or The Path or possibly Braid.
3. The human race has faced the appocalypse. Nomadic tribes will keep games as tokens of civilization despite the fact no one has electicity, an idea of how to play, or time for recreation.
Game most played: None