Even if Canonical only keeps a fraction of its desktop staff, they could easily improve on GNOME's default settings and theme, something that Fedora won't do.
It should be much easier since GTK+ "4" (not too many changes in GTK+3.x) combined with finally having a theme API, though the intention is to have some bits of GNOME run these development GTK+ versions at some point in future.
They're redoing how widgets work in GTK+ "4". That's basically like changing HTML and having slightly different elements. Though there's a theme API, I wouldn't be surprised if some theme work is needed as a result.
