I’m not sure if the RFL and clubs would be liable to pay any damages. I think that would be the insurance companies, the problem would be if the insurer has to pay out, then future premiums would be so high that the sport could not afford to pay the premium. No insurance = no one playing the game. That’s how I think could well happen if the injured players are successful in their claim. Then again I’m no expert on such matters.

I can't imagine it would be that simple, to just sign a disclaimer.

People do it all the time.
If you do a bungee or a parachute jump, you sign a disclaimer to say you understand the risks.

Employment law is a whole different thing, just signing a disclaimer isn’t going to cut the mustard i’m afraid. This class action (and possible individual claims to follow) really does have the potential to change the game as we know it if successful. And whatever the outcome i should imagine the the insurance premiums are going to sky rocket to become eye-watering levels.

That's a fair point.

This is not about employment law though as they are not trying to sue their employers ( the clubs ) but the RFL.

The RFL have assets of less than a million pounds so unless the RFL have an insurance policy then the ex-players won't be getting a lot between them. It is a sad position but how do they prove their illnesses have come about by playing a sport they all freely choose to do.