If the player with the ball loses his helmet, the play is automatically dead. It won't matter if the helmet is dislodged due to a hit or if it just comes off without contact. Keep in mind that this rule is already in place in college, so there is precedent.
Will it Pass?
In the spirit of keeping its players alive, the NFL should pass this rule without a problem. Naturally, it’s exciting every time Cowboys tight end Jason Witten loses his helmet and fearlessly charges down the field into converging defenders.
But at some point, something nauseating will happen to a guy without a helmet. If and when that happens, the whole world will wonder the same thing we’re questioning right now: Why hasn’t this rule be in place for years?