Depends on who sets the trend and how quickly that trend becomes generic.

I thought last gen Gears of War was going to kick off the new TPS trend. COD TPS, Halo TPS etc, but after so any Gears of War clones, the 3rd person shooter genre is pretty much dead now.

To be more specific this gen, sci-fi first person shooters are going to be more popular as well as open world games.

I think that open world action-adventures like Assassin's Creed and the Batman Arkham games will be strongly represented this gen.
Unless VR will be much more successful than I'm expecting... Then FPS maybe.

Tie between FPS and TPS.

FPS or TPS unfortunately.

If we're talking about quantity then it'll probably be Open World/RPGs, but if we're talking about sales then probably FPS. However, I think this gen we'll see more variety and no clear dominant winner.

I'm going to say action/adventure.

Grand Theft Auto VI
Metal Gear Solid V: The Phantom Pain
Uncharted 4
The Elder Scrolls VI
The Legend of Zelda U
Assassin's Creed Unity

Etc.

probably fp's.

I think horror games are going to make a huge leap in popularity up from last gen. In terms of the most popularity, I think FPS will get it again, especially since we will prob see VR headsets go mainstream this gen.

I think open world is the FPS of this generation.