Will Pokemon XY Remain the Highest Selling Exclusive This Gen? 

Only game that i could see beating it are Gran Turismo, which isnt likely or another Pokemon Game. Is there any other game? Or will it remain King...... for just Exclusives? :P

Most likely.

Probably.

Gran Turismo won't get close. I think it is more than likely to be X&Y

With the mega install base I think GT 7 will outsell GT 5 so that has the best chance, maybe Halo 7 could do it depending on X1 Install base

Yes. I can't think of any logical alternatives, and I don't think I need to explain why this, a game of nearly 13.5 million sales, is and will continue to sell ridiculously, though several people think OR/AS might beat because apparently it's pre-orders are topping X/Y's. I think this will remain the exclusive champ for the 8th generation. Gran Turismo, or if the Xbox One picks up steam, Halo will be on top for home console.

Uncharted 4 (homies)

ORAS won't even come close to XY numbers. If XY isn't the highest, the next Pokémon iteration will take the spot.

Only Pokemon can beat Pokemon.

lmfao XD. I would be surprised by anybody who didn't get that joke^