Tunable polarization properties in hybrid-guiding photonic crystal fibers infiltrated with nematic liquid-crystalline materials are theoretically investigated, both in the case of uniform switching of the liquid crystal molecules and for realistic nematic director patterns. It is demonstrated that the bandgap formation mechanism and the modal transmission properties in such fibers offer the possibility for electrically switchable, wavelength-selective single-polarization and/or zero to extremely high-birefringence guidance.