Actually, an FFL-like organization might be a good thing for the US to have in the future, as a cost savings device.
The FFL has some ground rules that a USFL would need to adopt. First of all, its officers would have to be active duty US officers. Next, it would be prohibited from entering the US, likely stationed on a Caribbean or Pacific island or atoll, like Johnston Atoll. It would be equipped to just be light infantry, with its transportation, logistics and communications handled by the US military.
On the plus side, it could recruit foreigners, not just US citizens.
Importantly, the *purpose* of this organization is not combat, but mostly low intensity, long term missions that are egregiously expensive for the US military to do. Using these personnel, such missions might be run for 1/10th the cost. Thus saving a LOT of money for our military to use on other things.
For example, a minor mission that lasts for six months and just needs “boots on the ground”, could save money in the tens of billions of dollars range.
You make a point, I do not know how it would sit with the upper ranks though, but that sounds good. A US Foreign Legion would need to have very strict training methods that are a bit on the old school back then, english only language just like FFL where French is the language you must learn one way or another even by force, 5 year contracts, and also depending on performance, or if they are wounded in battle, US citizenship if they deserve it but they have to master the english language and pass an citizenship exam.
Also one other reason why a USFL would be a great thing is the FFL in my opinion is an example of diversity and assimilation done right for regardless if you come from Africa, Eastern Europe, China or Japan you learn French, and the culture and leave yours mostly behind to fit in and legion members who come from this could become better citizens in my opinion.
While we are getting creative with organizing, let me throw an idea out I had about 10 years ago, when our National Guard troops were being repeatedly deployed in Iraq and Afhanistan. I thought we should actually have two types of guards. One, the traditional National GUard that would receive more military training, pay and deployments; and the other, the Home Guard, which could only be used in the territorial US. It would receive additional training in search, rescue, and policing, for disasters like fire, tornado, hurricanes and riots, and less fighting, weapons, and pay. Look forward to your thoughts on this.
“the *purpose* of this organization is not combat, but mostly low intensity, long term missions”
This is kind of what we face with the Iranian-backed militias like HizbAllah. The main difference is that they are semi-covert about owning them, to retain some diplomatic cover, and misdirection of their enemies.