This paper explores and reflects on the issues state policy needs to address in the long-term to support a transformation of K-12 education systems. Personalized learning and competency-based education systems, designed to ensure equity, hold promise to prepare all students for success in college, career and civic life. This report shares strategies for policy to support systems change over the long haul toward competency-based systems that ensure mastery and success for all students. This publication intends to spark conversation around core concepts that policy needs to address to achieve sustainable systems transformation toward personalized, competency-based education systems. It introduces four 'threshold concepts' to help us think differently about what is possible in an equitable future education system where all students succeed, and how to address deep-seated systems design flaws across K-12 education.