I do hope you are right and frankly feel the kind of quantity you speculate could well be there. However having invested in Gold Mining Juniors for many years I, and likely many on this forum, know a bit about hard rock mining.
You do indeed find the vein and then, from underneath, cut it away. This involves a special breed of miners because some of those veins/seams aren't that wide and they try to minimize the poor or unmineralized rock taken out with the gold bearing ore.
Now Noront at Windfall has several different kinds of gold mineralization in different zones. It's going to be extremely interesting to see results from bulk samples from all of those zones.
Hole 100 is freaky rich mineralization and you can count on the access going in right under it so they grab as much as they can for the 'bulk' sample. However if they have to start hard rock vein mining you can count on the Government insisting on full mining permit with all the health and safety sign offs.
The Windfall story has taken years to develop to the point we are at now. This is indeed both exciting and now very fast moving story that could yet surprise us all with it's value. This year Noront will finally have all the information required to make mine decisions. If underground work proves up huge and rich tonnage it's not unlikely a mill for on site processing will be installed. Depends entirely upon tonnage and years they can operate before taking everything out. Could always find more once they are underground and mining too.