Welcome, michans...No replies yet so I'll jump in just to point out that SNDXF is in good shape on either side of the gold price.
As you said, if gold retreats (assuming it isn't too long term) it puts advanced explorers in a higher risk position and enhances Sandstorm's bargaining position and future profit margin. OTOH, if gold breaks out, it brings a lot of new or more marginal players into the game, many of whom do not have sufficient access to capital without greatly diluting their float or putting themselves in a precarious financial position. (It also increases Sandstorm's income and potential share of newly-exploitable reserves, but these are more obvious benefits.)
The fact is Sandstorm should do well in either scenario, especially considering its minimum cash guarantees. This is in fact one of the many things that make streamers overall a better risk-reward proposition than the great majority of miners.