This paper is dedicated to the lifetime prediction of Type II modifications (i.e., nanogratings) written in silica glass using an infrared femtosecond laser. Herein we report accelerated aging experiments of such nanogratings through the monitoring of their characteristic linear birefringence signature. Based on the master curve formalism, we demonstrate that these laser-induced nanostructures can survive for 200 hours at 1100°C. Under the reported processing conditions and after a dedicated passivation treatment, the estimated lifetime of the birefringent optical elements is beyond 10 years at 800°C with a minor erasure of 7%.