To respond to the first part of your argument, I agree. It is fact and situation specific. And the outcome of this lawsuit will determine where we draw the line concerning employer vs. employee responsibility.
To respond to the second part. Nobody is talking about separated shoulders, or eye injuries. I agree, those are inherent risks which come with the game. I don't think you can get those out of the game without fundamentally changing the way it's played. But you absolutely can get rid of MOST head trauma without changing the game. Why? Because fighting and hitting the head are already against the rules. Individuals ignore the rules when doing those things. Make the penalties so stiff that players no longer ignore the penalty, and the behavior will stop. Sure, accidental hits to the head and/or concussions resulting from the head hitting the boards or the head hitting the ice will still happen. Nobody is talking in absolutes here. But if those are the only means of getting head trauma, and they're accidental, then it's reasonable to say that they're accepted risks because accidents can't be avoided Fights and head hits are not accidental, they're intentional, and they're a violation of the rules. It's not unrealistic for players to think that they can play hockey without being punched in the face or hit in the head. Just like they can (and should) expect to play hockey without being slew footed, or given a B.C. two-hander.
The reason that I mentioned separated shoulders and eye injuries is because your post stated:
Most of us live in a country that can send a probe to Mars, clone a sheep, or harness nature to create energy, yet you act like it's unrealistic (and unreasonable) for hockey players to want to play the game they love AND be safe too.
Hockey players will never be able to play hockey (in any form that is a semblance to what it currently is) AND be safe too. The game is not safe, it is violent, risky, and dangerous. I understand that your chief complaint is hits to the head and fighting but the point I was trying to make is that your definition of an employer's responsibility:
If your employer doesn't do absolutely everything in their power to keep you safe on the job, they're liable to get sued.
Well unless you're a Roman Gladiator it's the responsibility of your employer to make sure you're safe at work. That's true of every job in the civilized world, and it's true of hockey.
There are many things that would completely alter the game of hockey but would be required if an employer must do "absolutely everything in their power to keep [player's] safe on the job" and if "it's the responsibility of your employer to make sure that you're safe at work."
The line between employer/employee responsibility and also an athlete's assumption of the risk (which even the term over simplifies it, the legal term is volenti no fit injuria which translates "to a willing person, injury is not done.") For example the illustration that most law schools use is a boxer consents and assumes the risk of the dangers of being punched repeatedly with a gloved fist but does not consent or assume the risk of being hit with a baseball bat. To boil that all down to it being the responsibility of the employer to make sure an employee is safe and that hockey players have a right to play the game they love and be safe ignores to a large degree the violence involved with the the sport/occupation even at the best of times. Whether the league knew and hid information or failed to make reasonable efforts to eliminate unreasonable hazards from the sport.