Soccer is already an established sport in the USA and in Canada, I don't understand why it would be necessary to make it more popular. The sport is what it is and if it can't compete in the North American market then that just what it is, no need to change the most popular sport in the world because it is relatively less popular in one single market.

If OP thinks about this in reverse, hockey is a much less popular sport on the global stage than soccer. What rule changes should hockey implement to make it more popular in Mexico? Add 4 more blue lines to encourage shorter passes? Put in right angle corners rather than the curved rinks to discourage boring dump and change hockey? Replace the puck with a ball so it's easier to see and behaves more like a soccer ball? It would be ridiculous and create a sport even less popular world wide.

Add to this that many of the 'problems' these rule changes tries to address are already handled by already existing variations of soccer such as arena soccer and indoor soccer. As you would predict, traditional style soccer is much more popular even in the US and Canada than these variations. Soccer succeeds on it's own merit.

Here is how to make it truly appealing:

1. Relax the offsides rule if not remove it completely, I mean I understand that soccer fans despise scoring but come the fuck on.
2. Smaller field or double the amount of players.
3. Two balls, if the game goes to overtime you introduce a third.
4. Once you hit two minutes left in regulation (also just get rid of the arbitrary extra time for this to work) no more penalties.
5. The goalie is allowed to run with the ball in his hands indefinitely anywhere on the field, even throw it into the opposing goal if he is able, but once he leaves the box it's completely legal to kick him in the head.
6. Create a new position called the batter, one player on each team who is allowed to bat the ball with his hands (though he is not permitted to carry it) but is forbidden from kicking it.
7. Headbutting is 100% legal, but if the player gets a concussion from headbutting or attempting to headbutt someone else he must remain in the game and not allowed medical attention until halftime or the game's finish.
8. Games are played with purses like in combat sports, where the winning team takes the purse and the money is divided amongst players according to a percentage laid out in their contracts and performance incentives.  The losers get nothing.
9. Each team is permitted to place one tiger pit on the field and players aren't allowed to help their teammates out of the pit if someone should fall in. 
10. If a ball falls into one of said pits it is replaced with a new ball from the sideline.  However, players can venture into the pits and retrieve the ball and it shall be legal, whereupon the game enters bonus ball time where 3+ balls are played with until there is a score, whereupon that ball is removed from play.

since I am a real sports fan that appreciates nfl, nba, nhl, mlb and NATIONAL soccer, I'll tell you.

Firstly, there are too many gotdam leagues. We need a single clear cut league where the best of the best play i.e NBA. we dont need epl bundesliga italian etc. If possible, each nation should have its own team with the best players possible. ie England Lions, Spain Armada Italy Tigers etc. Theres a few reasons world cup is very popular in U.S and its bc theres a perception of superior quality vs league play, and also countries are easily indentifiable moreso than 'real madrid' or 'man u' which , no offense, americans can give two shits about. If its a world sport bigger than all, then it should always have contry representation, whether league or world cup competition.

And one more thing - shrink the field a bit and force the action. american sports fans appreciate speed, skill power and action. Not suggesting anything drastic but the field should be cropped a bit and lets just say substitutions rules etc should move closer to hockey style (no more red card nonsense, have power playspenalty box instead).

Follow my ideas and soccer would have its status elevated to a major US sport. right now its worse than golf and tennis status lol.

Less players, smaller fields, and then it might be more interesting.

so basically Futsal then lol

Honestly, I don't think the rules need to change in order for soccer to be popular, they just need to continue to raise the quality of the product (which is happening) and for the MLS to keep improving itself with officiating and regulations (which is happening at a slower rate than it should).