With companies pushing digital games over physical copies of games they actively control when can and can not play games which they were previously unable to do with physical copies of games. However,Electronic Arts is making an unclear move now by shutting down their Rock Band game for iOS but that is not stopping them from continuing to sell it until the last day on the App Store.
Unlike traditional ways of games being discontinued, EA is disabling the games on all iOS devices by the end of this month and has no immediate plans to give a single user a refund. But if it makes you feel better they are only selling the game for $4.99 now instead of the $9.99 price tag they had when the game launched in 2010.
EA has made no statement about the shut down and there is also no warnings on the games page but I assume the shut down and disabling of the game on the devices is due to music license issues and royalities. So, if you have purchased the game prepare to be angry and get all the use of the game you can now.