There is no way of really predicting and anyone who says there is, is only stating their own views.
10 years ago, there's no way anyone could've predicted that a game like Minecraft, with it's blocky retro style, would ever be as popular as it is today.
Hence my view that it's impossible to predict.
Generally, games that come out tend to be rehashes of popular formulas, even down to the general thread of the story (Disaster, War, Take Sides, Fight in the 'Final' Battle, New Enemy appears, repeat for MMORPGs). It's rather sad to see, to be honest.
In the past few years, I've taken to watching Kickstarter, reading gaming news out of E3 and other gaming cons, etc. and finding gems in interesting indie games like Kerbal Space Program, Planet Explorers, Star Citizen, and the like. That's where the future really will lie--in innovative and new approaches (or the rebirth of old approaches).
Grei