Ah, so the deal was before Xamarin bought the rights to Mono from Attachmate/Novell, I didn't know that.
>At the same time they are working hard on their own proprietary il2cpp (to export to C++). The writing is clear: they will drag things as long as possible with using their old version of Mono until they are able to switch to il2cpp.
From what I understood they would still ship Mono as part of Unity (as in development framework), however what they want to avoid is the license costs that comes with shipping the Mono runtime with each Unity game, hence il2cpp, but perhaps I'm mistaken here ?