Six forces are shaping in-store retail media through 2027: screen networks moving from pilot to chain-wide scale, place-and-time intelligence becoming the planning layer, analog and digital inventory merging into a single in-store offer, retailer-built custom formats commanding premium rates, AI taking over campaign operations so tail and torso advertisers become economic to serve, and measurement moving from foot-traffic proxies toward store-level sales lift. US in-store retail media ad spending is forecast to climb 33.1% in 2026 from a base still under 1% of total retail media spend.