I watched a boys regional final a couple of years ago, when after the game, the ref got a little overzealous and red carded several players from Madison Academic. The players who weren't seniors had to sit out the first two games of the next season.
As to the faint lines, referee's could call a game and not allow it to be played because of the lines, but I imagine VERY few coaches would ever want a game called because of faint lines. At worst, it would seem more reasonable to bring it up with the coaches who should make sure the players are aware. I've been in many a game where the lines were faint, though usually its the sidelines. Did a game just last week where the grass had been cut short the day before and the cutting made all the lines very faint. And been in down pours where the lines disappeared in the middle of the game. But the games go on "as if the lines existed". An unfortunate event.