So i overlayed all the relevant frames from the replay
Green Line: ideal racing line
Red Line: the one Lewis wanted to take
Blue Line: the one Rosberg wanted to take (judging by his trajectory and him not turning in until the moment marked with the blue X - that's where he reacted to Lewis turning in)
Light Blue Line: Rosberg ended up on it after colliding with Lewis (marked with red)
Pink Line: Lewis ended up on it
marked with yellow-ish is the room Rosberg was left by Lewis, who approaching the corner was in front.
As i see it Lewis went on a line that is the 'ideal' line just further to the outside or 'later' if you will - Rosberg (as he admitted in his FB vlog) just wanted to go straight and turn in at the last possible moment ... does anyone remember the Rossi - Marquez incident last year in MotoGP ? It was very similar.