I'm glad you can make definitive statements on hypothetical events, you must make a ton gambling.
Cavani was having an excellent tournament. He has historically shrunk under the pressure but he was playing extremely well. Portugal is average but Cavani was great, Russia is still alive and Cavani helped smack them around.
France still wins because they're insanely talented in the attack but you can't automatically discount a very good forward.
Were we watching the same game? Japan got two across sure, but Brazil only managed one on 20+ shots. Courtois is one of best five keepers in the world, only a dummy would argue that.
France has more options, but discounting the trio of Lukaku, Hazard and de Bruyne isn't smart. Lukaku has absolutely been as good as any attacker in this tourney.