If I remember correctly Unity was a fork of Gnome with lots of patches applied to the point of having both Gnome and Unity on the same system taking effort and being risky w.r.t. stability.
My guess is that they've invested entire Unity vNext on Mir, and if they're dropping Mir, they'll might as well drop Unity 8. That leaves them with Unity 7, and to unfuck a decade worth of changes they've done to make it work with mainline Gnome source.
Basically lots of work to have a 6 year old product back to square one, before they can, once again, attempt to further develop it.
I'm guessing they've decided that's not worth the effort and that their time is better spent helping improve something already mature (Gnome 3).
Touché, but they could have listened to the community back when they announced Mir and Unity 8 too ;)
They reduced the number of patches quite a bit. For some of the things they do, they depend on components that are not commonly used within GNOME. Meaning, it's not a patch, but as a sole user they'll have to maintain components if they're the only "user". Something written on top of Tracker IIRC; not started by Canonical, but nicely used by them. That's always a bit of a difficult explanation, sometimes Canonical expects maintenance to happen magically.
My guess is that they've invested entire Unity vNext on Mir, and if they're dropping Mir, they'll might as well drop Unity 8. That leaves them with Unity 7, and to unfuck a decade worth of changes they've done to make it work with mainline Gnome source.
Basically lots of work to have a 6 year old product back to square one, before they can, once again, attempt to further develop it.
I'm guessing they've decided that's not worth the effort and that their time is better spent helping improve something already mature (Gnome 3).
Touché, but they could have listened to the community back when they announced Mir and Unity 8 too ;)