I was reading the ESPN article about instant replay in World Cup soccer and imagining how horrific that would be. Imagine all the stoppages. I suppose they could have some challenge system like in the NFL.
Of course, any such system is very limited since they need to be limited to stoppages of play, of which there are plenty in the NFL. From what I see, the only substantial stoppages in soccer are halftime and after goals are scored. I suppose they could allow challenges when you team has a corner kick or is throwing the ball in, or when the goalie is holding the ball.
One big problem is if time passes after the missed call, how do you roll back time?
I wonder if certain sports can ever recover from the number of camera angles currently available. There will always be plenty of poor calls in every human refereed sport that fans unhappy with outcomes can fixate on. Some are directly relevant, like the goal the US didn't get. Others invite speculation of what could have been.
In the end, humans are calling these games and you have to make a choice between allowing faulty human judgments, or fundamentally disrupting the game.