Yes, the only way is up for copper. Why else is BHP pumping $3B to expand Olympic Dam and have been advertising 'copper the future' on TV every day.
NST has been supporter of VXR since 2012, can't be for charity. Once VXR gets EPA go ahead and some endorsement from banks / off-take, it will fly. The time to take over is now or never before it becomes too expensive.
Can't see the logic in a NST+VXR JV. They flagged that years ago, but times have changed since then.
Anyway, which ever is the better business case, only the inner circle will know.