I'll take a shot: Nothing, if you don't believe current levels have been run up by specs and manipulation. If you do believe current levels are a fairly close approximation to actual combined industrial and investment demands, the only thing that would drive it down would be a vast pool of cheap silver being discovered. It won't be due to vast amounts of the real stuff coming onto the market because increasingly, it is in strong hands. The paper sales just encourage the physical uptake. That has been both the gold and silver story since the spring.
Look at the ridiculous reasons being given now: "With the SNB guaranteeing a dilution of the franc, it's risk on again and PM suffers." Really? One of the very few asset classes that could compete with PM is being groomed to be shot down and that's bad for PM??
See also: Rising dollar. Easy to dispose of. Both silver and gold have done great in rising dollar environments, that canard is old hat and has almost no staying power.
Margin lifts: So what? Specs are leaving, to be replaced by REAL INVESTORS. Raise it all you want, I've made plenty unmargined.
What today is, is just a reprise of the scare headline and robo-thinking that has missed an 11 year bull market. Don't be a chump and listen to the same folks who have been wrong FOR MORE THAN A DECADE. There is still a lot of upside, the downside is transitory and weak in staying power.
When all the paper money is confetti and you're trying to be happy about your 10-year Treasury note interest payment at least than six months' inflation, who ya gonna call?