Minimum salary would be $750k if he makes an NFL roster, even above $200k if he only makes a practice squad for an entire season.Surely he must have had some unofficial discussions with a team(s). Be a hell of a gamble if not, he’d probably get an easy 300k+ offer from a number of union clubs
Even if he fails I reckon he could just return to rugby and still get a top-end contract given how talented he is and what he's already shown at a young age? Low risk, high reward move to me.