I don't think there will be much of a difference with another guy. I'm a coach myself, not icehockey but another teamsports. The influence you have during a game is so limited sometime.
And rosterwise there isn't much he could have done differently I guess.
Fischer failed to get the team ready for the quarters. They came out not ready in the first period the last two games too and today the same issue. The first line worked significantly better with Kurashev but Fischer insisted on leaving Riat on it. Its not even like the third line with Kurashev played that great since Scherwey went down. Sure the loss isnt on Fischer alone but you can expect the team to have a better gameplan against a team with very good goaltending than just to take volume shots from low danger areas.. A coach can have a huge impact on the outcome of singular games and tournaments. Just look what Jukka Jalonen is doing with Finalnd year in year out, often with worse player material than we had in those tournaments. I wouldnt even question Fischer however if his track record outside the group stage wasnt so bad overall.
I also dont like the "there is no alternative to Fischer" argument. The Czechs just hired Kari Jalonen and are doing fine. And there are some Swiss alternatives like Cereda too. Those are not perfect solutions but sometimes you just have to take a leap of faith.
this was a perfect example how important goaltending is. swiss don't have good goalkeepers since years
Genoni used to be good up until a few years ago but he has been on the decline internationally for a couple of seasons now. Whoever coaches the next WC needs to build up JVP and maybe Schmid sooner than later as the coming tandem.