2.5 years is about right because you never take full value of indicated measure
if taking 50% of indicated + 100% of measured @ 1.6MTPA, then it gives about 4.5 years.. but this DFS is about 2 years old.. and so about 2.5 years left..
It's quite hard to make the other 50% of profitable especially given that the $/tonne is expected to go down.. even though I reckon prices will go down in 2018, but what about 2.5 years later? There's also the cost to reach that other 50% of indicated measure.. (ie: Opex will increase to dig it up)
Mt Cattlin has been shut down before to it not being economical.. so there is a high risk that it could go that way again.
This is why SDV is ultra important..and I believe a huge CR is needed to spend $500M to get it up and running. If no SDV, and Mount Cattlin is only way forward.. GXY cannot justify its current market cap.