Those who see potential in paywalls include investor Warren Buffett, former Wall Street Journal publisher Gordon Crovitz, and media mogul Rupert Murdoch. Some have changed their opinions of paywalls. Felix Salmon of Reuters was initially an outspoken skeptic of paywalls, but later expressed the opinion that they could be effective.[21] A NYU media theorist, Clay Shirky, was initially a skeptic of paywalls, but in May 2012 wrote, "[Newspapers] should turn to their most loyal readers for income, via a digital subscription service of the sort the [New York Times] has implemented."[22][23] Paywalls are rapidly changing journalism, with an impact on its practice and business model, and on freedom of information on the Internet, that is yet unclear.[original research?]