I figured it was only a matter of time, and I think they made the right move in dropping Unity.
It never gained the traction that Cinnamon attained. And with Gnome, KDE, and xfce already established, it's becoming increasingly obvious they lost that bid for desktop supremacy.
Besides, Unity was bone ugly and geared for what Shuttleworth was convinced was "the next big thing" (that didn't come to pass) for the desktop market - the touchscreen.
I don't think Unity will be missed. It was mostly a distraction for Cannonical IMO. With that clunker out of the way maybe Ubuntu will get some of its groove back.
Truth is, all Canonical would need to do to go back to the top distro slot is to embrace Cinnamon. Do that and they could suck the wind right out of Mint's sails. Because all Mint did was take Ubuntu and give the users the desktop experience they actually wanted rather than try to pull a Steve Jobs move and try convince them Cannonical's corporate "vision" of unity was what they really wanted.
If Cannonical offers a better Cinnamon based interface, Mint becomes superfluous.