The answer to fragmentation of the line is:
-2x iPad Pro , a 10.5 inch and a 12.9 inch with similar specs and a few exclusive iOS 10/11 features(simple file management and multi account by touchid for example.
-1x iPad 9.7 inch
-1xiPad SE. 7.9 inch iPad
-2x iPhone pro, 1x5.8 inch and 1x 5.1-5.2 inch with oled, dual cams, etc, perhaps even a form of split screen , touchid embedded in screen, curved sides, etc.
-1x iPhone , 4.7 inch
-1xiPhone SE, current 4 inch
They only need to add a MacBook SE , something like an updated MacBook Air 11 inch under the se name, and their entire mobile line-up makes sense.
For the desktops, drop the Mac mini and the Mac Pro, and then release:
1x iMac pro: upgraded and better specced 27 inch 5K iMac
1x iMac , 21 inch 4K
1x iMac SE, 21 inch iMac at 1920x1080.
Or something like that.
So an ES line for a value line , than a regular line, and a real high end / tech line-up.