AFAIK we will release alternative binaries without C# support. The reason for this is that the mono runtime sizes a lot, so it wouldn't be fair to impose that on users that won't use it.
The main language will still be GDScript, and the documentation examples will be written in GDScript.
Actually, it's quite easy to convert GDScript examples to C# yourself. The API is the same, it's mostly syntax and few features that may differ. I will document all of these differences.
We will also provide demos translated C# on this repo. Right now, there is only the old platformer 2D demo (the one that still used RigidBody2D). First, they will be translated "as is", later the plan is to make them more C#-ish.