Good piece in big picture but I feel you're assuming a bit too much. The U.S. has a base in Dijbouti. It's certainly possible the ships could become depleted with enough attacks but the attacks haven't come close to that. F-16s are also used.

Economically your point is good. Further, The rate of manufacture of those missiles is unknown. Is the U.S. keeping up or not.

Lastly, The U.S. doesn't need oil from the Middle East. That isn't to say the attacks aren't significant.