Not my personal opinion. I believe the interpretation is in the Rule itself. "At the snap, at least Five A players on their line of scrimmage must be numbered 50-79." This rule does not change but the numbers can. There are two exceptions to this, 1-3 & 4th downs. On 4th down when team A is in scrimmage kick formation, with the exception, these players can be REPLACED by players with receiver numbers. The requirement of FIVE legal linemen is still in effect, just the numbers have changed. With the new scrimmage requirements, if there are more than five in the formation the players who are in under the exception MUST line up between the ends and are ineligible during the down. Furthermore, by rule, if there are only FIVE linemen in the formation with receiver numbers, even if they are on the end of the line, they all would be ineligible because they are in the game under the exception, in other words, they are in effect lineman normally numbered 50-79.