Accelerator-based neutrino experiments require precise understanding of their neutrino flux, which in conventional beams originates from meson decays in flight. These mesons are produced in high-energy hadron-nucleus interactions in extended targets. The cross-sections and particle yields of the primary and secondary hadronic processes involved are generally poorly measured, making hadron production the leading systematic uncertainty source on neutrino flux at all major experimental neutrino facilities. The NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) multi-particle spectrometer at the CERN North Area has established a dedicated program to make precise measurements of hadron production processes for neutrino beams, and has taken data on processes important for both T2K and the Fermilab long-baseline neutrino program. This talk will present recent measurements of hadron production cross-sections at multiple energies and targets, as well as more specialized measurements using replicas of neutrino beam production targets. Detector upgrades underway in CERN's current Long Shutdown 2 will be discussed, as well as prospects for future measurements including a possible new low-energy beam facility for NA61/SHINE that will broaden the physics reach of the experiment.