How do you value gold equities when they are doing this well?

Between 2000 to 2014, ASX gold producers were collectively cash flow negative or neutral, in terms of operating and investing cash flows, and using annual financial numbers. In 2015 margins exploded due to both excellent cost discipline and metal price movement. So gold producers are suddenly achieving multi-cycle high cash returns. Cash flow is the basis of most valuation methodologies, but how do you price an industry that is doing this well? I also believe a rotation is now taking place. Investors who have made profits are looking to recycle some of those, and to take some more risk. This is lifting smaller gold stocks like explorers and also rubbing off on miners of other commodities. There is certainly a sense of investors looking for “what next”, and with the heat seeming to have come out of base metals falls then I suspect they are likely to be a beneficiary of some of this interest.