Apple's next iPhone won't be until late 2016, but should come with a new design.
Original iPhone Will Soon Be 'Obsolete' In Apple Retail Stores
Apple typically makes products 'obsolete' or 'vintage' five years after they are discontinued, though there are some exceptions where required by law. The original iPhone went on sale in June 2007 and was discontinued in July 2008 when the iPhone 3G was released.
Other Apple products that will be considered 'vintage' as of June 11, 2013 include the mid-2007 models of the iMac, the late 2006 model Xserve, and the original Mac Pro. 9to5Mac has the list of newly minted vintage and obsolete products, while Apple maintains a list of all products named vintage or obsolete going back to the Apple II.