Here comes the Gold, page-16

AUD gold still well over $1,700/oz.

AUL don't need very many tonnes to justify current MC or MC @1.3c.

On a sustained production for x years going forward, who knows, but we have to remember what the intention of trial mining is - nailing the end product to provide confidence in assumptions.

I don't see any majors interested in an 80kt operations, so I'd say that is the most simple reason a major isn't there now. That doesn't mean small, short life projects can't be profitable for small producers.