Availability of the Menu Key
There is no real standard here — every manufacturer does whatever it likes. E.g., many Samsung devices (including Samsung Galaxy S4 and Samsung Galaxy Note II) use the traditional layout — Menu, Home, Back (with Menu and Back as touch keys, and Home as a physical key; and the Back key is really on the right side, while many other manufacturers place it on the left side). Given the Samsung market share, there is a significant number of phones shipped with recent Android versions and still having the Menu key.