It seems to me that the worst thing that can happen to Neymar is that he will have to miss a couple of games, this is a minor injury and should not lead to more significant consequences. Brazil already have 3 points and in the remaining two games of the group stage they need to win at least once - this is an easy task given that their opponents are not so strong, so there is no danger that the absence of Neymar will be important. And to be honest, I think Brazil, even without Neymar, will score 7 or 9 points in the group.