Well, I am big fan of Ubuntu and it's a sad news for me.
At the same time I am not much surprised because there are many other similar projects are either already failed or are at the verge of failure: Sailfish OS (made by ex-NOKIA employees), Firefox OS, Tizen (by Samsung Intel and others).
I feel like, Android is the key player here and somewhere responsible for the failure of other OS'
Android has already killed the Windows mobile OS completely and here is a news for all of ya:
Android now the world's dominant OS, surpassing Windows