I don't think it is the case that they had always planned to build a whole new software stack. And that's not even what they're doing - Ubuntu runs loads of 'Linux ecosystem' applications, which Android never aimed to do.
On the system level, only last year they were talking about one day moving to Wayland - which they later decided against for reasons I don't know enough about to judge. My understanding is that they only made Unity because they felt they didn't have enough influence in the design of Gnome 3. I don't think there's as much of a master plan as you suggest.
On the system level, only last year they were talking about one day moving to Wayland - which they later decided against for reasons I don't know enough about to judge. My understanding is that they only made Unity because they felt they didn't have enough influence in the design of Gnome 3. I don't think there's as much of a master plan as you suggest.