My Prediction for 2Y Luffy:

His hair will be longer, more like Ace
He'll have a memento to Ace some how; maybe goggles like Ace and Sabo had
He'll be more mature looking
He'll have a few new scars, but not on his face
His sense of style probably wont change

:)

Just a quick sketch, I wanna be sketching a character a day until One Piece comes out!!