In Short

The BlackBerry 9720 is a BlackBerry 7 device set to be launching later in 2013. While things have moved ahead to BlackBerry 10 with the Z10, Q10 and Q5, BlackBerry is releasing an updated BlackBerry 7 device that will run OS 7.1 and follow up on the Bold 9780 and 9790. 

The 9720 features an updated BBOS 7.1 with some features from BlackBerry 10 (like a quick camera button and new lock screen). The 9720 also have the navigation buttons from the 9790 as well as a very similar (if not the same) keyboard to the BlackBerry Q5.