OPEC is set to regain its dominance as the leading source of new oil supplies in the late 2020s as total non-OPEC supply growth plateaus around 2025, well before demand peaks. Our oil market service Macro Oils long term forecast shows OPEC's importance to the market will shift over the next decade from restraining production currently, to needing to grow capacity to meet demand. OPEC producers will hold sway over the market as the key source of growth through the mid-2030s, when oil demand peaks as the energy transition drives fuel efficiency gains and electrification of transport. However, non-OPEC producers will capture the bulk of contestable demand in the near term, driven primarily by increasing US tight oil production. This Insight explores the changing dynamics of the long term oil market fundamentals.