The New York Times notes that while there's no specific mention within the letters of punishing companies with legal action if they refuse, that "a person with knowledge of the group's thinking said that if the retailers did not act voluntarily, a push for reform or litigation could be a step down the road."
Although the Los Angeles Times couldn't reach Kroger; Walgreens, Safeway, Walmart and Rite Aid all stated that they were reviewing the letter. Rite Aid said it "'appreciate[s] that the attorneys general took the time to share their views' and that it is evaluating the letter."
A study by the Center for Global Tobacco Control says in 2009 less than 5 percent of tobacco sales occurred in pharmacies but predicted that amount would rise to almost 15 percent by 2020. (Via National Center for Biotechnology Information)
See more at newsy.com.