I can think of one U.S. company that's almost wholly dependent on Chinese suppliers: Wal-Mart. Never underestimate the long-term stupidity motivated by short-term greed.
My skepticism regarding potential Chinese scandium supply stems from simple math. At the concentrations of scandium found thus far (in the few hundred ppm range), the Chinese would have to process a huge amount of material to get several hundreds of tons per year. Even if it's a byproduct of some other mined material, that is a whole lot of dirt to move.