Amazon is considering an annual library subscription model on its upcoming tablet computer device that could dramatically change the way books are consumed at the world's largest bookseller, The Wall Street Journal reported Monday, according to dpa. Analysts have already identified the expected tablet as the device most likely to pose a challenge to Apple's sector-defining iPad, given its expected 300-dollar price tag and tight integration into the company's online store, as well as music and video services. The ability of readers to purchase a yearly e-books subscription could further boost the attraction of the Amazon device, even though the library model would initially at least be limited to older books, the report said. Some publishers were unenthusiastic about the plan, fearing that it could lower the value of books and strain their relationship with other book retailers, the report said. The subscription model would reportedly be offered to customers of Amazon Prime, who currently pay 79 dollar a year for free expedited two-day shipping and access to a digital library of films and TV shows.