I will watch this league if they adopt any 3 of these rules:
Make it, take it. When you score a touchdown, you get the ball back on your 25 yard line. If the other team can't stop you, that's their problem. Down by 4 scores in the 4th quarter? The game isn't over, you still have a chance if you can keep scoring touchdowns. If you only get a field goal, you still have to kick off, because the other team kept you out of the end zone. Go for touchdowns more often, less field goals.
20-second play clock. Cut way back on guys standing around in huddles, get more action in there. Less substitution means more well rounded players, and less waiting around for players to run on and off the field. Harder to run out the clock at the end of the game, and less taking a knee.
Leather helmets, no facemasks. No more helmets as concussive weapons. Let's see the players' faces.
Offensive holding is legal. Take away the most random calls in the NFL. There's holding on every play anyway, but it's only called once in a while, which is insane. Let everyone grab and pull. The defense can grab and hold and to tackle a runner, even tackle by pulling the shirt, so let offensive players do that too. if you want to pressure the QB you will probably have to blitz several guys.
Pass interference is legal. Take away the second most random calls, that are also the most impactful and controversial. No more Flacco incompletions that gain 60 yards. This makes passing a lot harder, but the other rule changes will make offense in general easier and defense harder.
Offense can line up in any formation they want. The defense can line up any way they want, so why not the offense?
A catch is possessing the ball with both feet or a knee inbounds. If you possess the ball with both feet inbounds but drop it going to the ground, it's a catch and fumble. The ref makes a judgment call if the receiver has possession or not.
All offensive players are always eligible receivers. Why can only some players catch a pass? Why shouldn't the defense have to guard everyone?
Once all offensive players all come set, they can move as long as they don't cross the line of scrimmage before the snap. Take away stupid false start penalties and let the offensive players do what the defenders can do. Once all offensive players are set, the ref blows the whistle, which is the signal that they can now move and/or start a play. No whistle until they are all set, no play can start until there is a whistle.
Any play/call can be reviewed on video if a team challenges it. Teams have 3 challenges per game. If they win their challenge, they don't get charged. Officials have no more than 45 seconds to come back with a ruling once the challenge clock starts.
There's no "breaking the imaginary plane" of the end zone. To score a touchdown, you have to possess the ball with both feet or a knee down in the other team's end zone.
End zones are 20 yards deep. Goalposts stay at the back of the end zone.
Offensive team fumbles out of the end zone, they get the ball back at the spot of the fumble.
One time out per team per half.
Punts that go out of bounds are a 15-yard penalty from where they go out. Punting is dumb and boring, there should be less of it, and when there is a punt, there should at least be a punt return. Punting out of bounds is extra boring and passive-aggressive. If you insist on doing it, pay a price.