How about this?
Groups of three - all teams play each other using half they squad at the same time.
So let's say you had England, Brazil and USA
England vs Brazil (Hart, Sturridge, Vardy, etc)
at the same time: England vs USA (Forster, Rashford, Kane, etc)
at the same time: USA vs Brazil
That way twice as many fans can watch their team, by using two stadiums at once. This will also help sell Samsung Triple-TV-TVs for fans that want to watch everything.
Then to make sure no one goes out unfairly, all three teams play another double-match against teams from "grouped groups". (Groups A-D are grouped, groups E-H are grouped, and so on)
Group A winner plays Group B third place and Group C third place
Group A runner up plays Group B runner up, and Group C runner up.
and so on.
That will mean each set of 12 teams have each played 4 matches. Top 8 go through.