Unity would have to fork Mono, as would Gnome and Canonical and Redhat, etc... The comments here seem very trusting of Microsoft. If it was Oracle a fork would be a given.
I think they're already using their own fork of an older Mono version. They couldn't work out a mutually beneficial licensing deal with Xamarin to keep using their newest Mono versions or something.
I think Unity have a good relationship with MS, so Mono being moved to MS should be good news to Unity -- for a while.
I think Unity have a good relationship with MS, so Mono being moved to MS should be good news to Unity -- for a while.