"Copper oxides, also known as cuprates, are the most promising materials for superconductivity. Today, cuprates can be superconductive at temperatures as high as -150 °C. But for many years scientists wondered why they lose superconductivity when concentration of electrons drops below certain level. Most scientist thought that the cuprates gradually became insulators.
Scientists from Université de Sherbrooke discovered that the loss of superconductivity is because of a sudden appearance of a distinct electronic phase in the material that enters into competition with the superconductivity and weakens it. It means, that higher temperature superconductors will be possible if we can get rid of the competing phase. This new approach opens a way to get an ambient temperature superconductivity."
Yep, catastrophic failure can be well, pretty catastrophic, especially with those type of flywheels.