The IceCube Neutrino Observatory is a cubic-kilometer Cherenkov neutrino detector located in the glacial ice at the geographic South Pole. DeepCore, a denser sub-array within the detector, has a neutrino detection energy threshold of less than 10 GeV. In recent years, IceCube opened a new window for measurements of the atmospheric mixing parameters in ice and became one of the leading instruments measuring atmospheric neutrino oscillations. Furthermore, its data serve as a probe of new physics beyond the standard three-neutrino paradigm and limit the allowed mixing between active and potential sterile neutrino species. This contribution discusses IceCube's most recent measurements of $\nu_\mu$ disappearance and $\nu_\tau$ appearance, searches for sterile neutrino mixing, as well as future in-ice measurements of fundamental neutrino properties.