Unlike previous years there are no sudden heroics to be had on Johns' part in this one. He is out till next season as far as I'm concerned, his performance next year is far more important than a high-risk premature comeback this season - stay off the field is what most genuine Knights fans will want, so too his doctors.
In any case the Knights are performing quite well in his absence, and although they may not win the premiership, they're learning a whole lot without Johns there.
It is important for both parties; Johns and the whole side, that the injury is left to heal properly, Johns is allowed to restore his strength and get some fitness back for next season. I'd be disappointed if Johns made a premature comeback - especially given the seriousness of the injury.