"The cookieless future" describes a state of digital marketing in which access to third-party cookies, such as those set by Google, Facebook, and other app developers, are unreliable as sources of consumer information due to limitations imposed by Apple (e.g. making data collection opt-in) and other companies as well as legal frameworks like GDPR and California's Consumer Privacy Act.
The absence of third-party cookies means that companies will need to rely more on first-party data about their uses to meet consumer expectations of highly personalized digital experiences.
According to a post in the MIT Technology Review sponsored by Adobe in April 2021, just 37% of organizations felt "very prepared" for the cookieless future.
MIT Technology Review Insights. “In a Cookieless Future, Half-Baked Marketing Won’t Do.” MIT Technology Review, April 28, 2021. https://www.technologyreview.com/2021/04/27/1023164/in-a-cookieless-future-half-baked-marketing-wont-do/.