They already do this in Korea. I don’t know if they are actually changing prices moment-to-moment, but they are using e-ink price tags that are impossible to distinguish from their printed, paper brethren. I saw one glitch out one day, and that was the only way I could tell. I mean, I guess I might be able to tell if I hunched down and inspected one closely, but it seriously looked identical to the same old printed ones at a glance.