We are specualting - so we could all be wrong when we get final information. But, let's think logically a moment. The statement in the document is: "The foul for twelve men on the field, whether a live-ball or a dead-ball foul, carries a 5-yard penalty."
Well, a "Susbstitition Infraction" (or Illegal Substition, whatever your term) has always been a 5-yard penalty, whether live-ball or dead-ball. There is no change there, so what could they be talking about? The only things related to substitution that were (are) 15-yard penalties are simulated replacements or substituions to confuse opponents - an unsportsmanlike conduct (9-2-2 Unfair Tactics) foul, and Illegal Participation, a 9-1-5 Illegal Interference Foul. The former does not involve 12 players on the field, so they arent talking about that one. So, they must be talking about Illegal Participation. So, by deduction, it would appear that Illegal Participation will now be just a 5-yard penalty.
The final statement in the Editorial Changes reinforces this logic. "Fifteen yard penalties are reserved for personal fouls, unsportsmanlike conduct fouls, and pass interference." That certainly reconciles with the Substitution Infraction thing.
But, moving one step forward, how does that last statement reconcile with Illegal Kicking & Batting? KCI? Delay in starting a half? Marking the ball? Changing numbers to deceive? Many others.
Obvviously, more to come.