It's a mighty good option to have when you are negotiating with Microsoft. Imagine Google offering to Microsoft that they would adopt Microsoft development tools and technologies iff Microsoft kills Windows Phone.
I think it's far more likely that any movement towards C# on Android would be motivated by: 1) perhaps enough devs are asking for it, and 2) it would give them extra leverage in negotiations with Oracle about Java.
Plus, if they make a deal with Microsoft, Samsung can't come along and make the same deal with Microsoft for Tizen tools.
It's all about the mobile ecosystems and it's something that Microsoft and Samsung will ever have.