I think your are correct, which was my whole point. It hasn't been shown because there is the issue of how to monetize with so few opportunities for commercials.
Perhaps your other points on how monitization is changing are correct. However, you mention that Fox, NBC, ABC/ESPN have soccer packages, but aren't these all shown on the lower tier sports channels affiliated with these organizations? I don't ever remember seeing a non world cup soccer event shown on a national TV Network, where as I have seen plenty of NFL, MLB, NBA, and NHL games nationally televised. Even regular season games.
Until you start seeing the same for Soccer, I don't think it will approach the national prominence of the 4 major sports here in America, and I still think it is due to the difficulty in monetizing to the viewing audience. Major networks won't show it unless they can recoup their costs in Advertising, which for television is still primarily via a commercial. Because the major networks have trouble with that monitization, they can't offer the huge TV contract payouts to teams. This leads to smaller salaries for the players, which leads to the better athletes playing other sports (with better salaries) in this country.
BBQ