I agree with BRex on the offsides being miscalled most of the time. I don't want to sound vain but I was quick enough to beat the defender when the pass was made and yet was called offsides frequently because of where I received the pass. Having said that I would take away the rule. The reason I would is found in the NBA where they keep changing the defensive rules to open up the scoring and teams just find a way around it and turn into the Pistons and the Spurs who keep winning titles with the most boring style of low scoring play ever!!!
The beauty of soccer is the understanding of the game that allows the specator to watch the build up of a play and see the culmination of it with a goal in the back of the net. Is it a game for everyone? NO! Just like hockey if you ask me. But is there a niche that can be filled by it in the USA? YES! Will stadiums be packed like overseas? I don't see that for many generations if ever. But will it be a viable sport that can be sustained by the fan base it has and will get in the future? Yes. I believe it will.
Having said that, I would offer these changes as possible improvments:
1) For every five (insert your #preference here) fouls called on a team during a given game the result would be a one on one PK but not the traditional place the ball 12 yards away and run and kick it. It would be a true one on one with the keeper like hockey where the ball is advanced from 30 or so yards out and shot within a prescribed time limit. Hopefully this would discourage the embarrassing flopping that takes place.
2) Like indoor soccer already does, impose a 2 minute man advantage for intentional/dangerous fouls. Allowing "power plays" would give the offense a chance to be up one man and hopefully score more frequently.
3) Eliminate shoot-outs to decide games. As a HS senior we (WX) played Bountiful for the state championship and it ended with a shootout with our asst. coaches son sending the ball over the posts for our loss. If the game cannot be settled on the field in a prescribed time frame the reschedule it. Or
4) Add more substitutions. This is one rule that needs to go for sure. Why have 18+ players on a team when the maximum you can play in a given game is 14 IIRC. (11 on the field with 3 subs max)
Otherwise, I love the game and will continue to watch and play as often as my time permits!
Go Cougs!!!