If this can be used to open up more platforms, without crazy licensing fees as with Mono and mobile devices, I think it is a very positive step forward.
No - Mono has crazy licensing restrictions and massive licensing costs for statically linking their framework. Xamarin offer a better option, but there is no "free" alternative using C#, nor could you create one with the Mono framework. The CoreCLR does have the possibility to get around this as the code required for creating a solution is not licensed in the same way. Xamarin's entire business model revolves around the fact that static linking is not allowed using the Mono Framework as a basis.
I think their business model revolves more around selling their proprietary bridges from Mono to mobile platforms' native APIs (MonoTouch and MonoDroid, now marketed as Xamarin.iOS and Xamarin.Android).
No, that's not really true. Their business model revolves around licensing the mono runtime to end users (in this case Developers) along with some extra platform specific code. In the case of iOS that is a statically linked exe build from AOT compilation of the CLR code. For Android that is a runtime that sits on the device and is shared for each exe, and for Mac that is taking the Mono Runtime and moving it in to the App package.
Yes, iOS was a lot of work. Yes, if they want to make it a commercial venture, that is their right, but Miguel has gone on record stating that no one else can do this due to the way the Mono runtime is licensed. They refused to give a static linking exception, as some other libraries do, so basically your only option is their solution or your own written from scratch. This is why the CoreCLR is cool.
Also - did you notice Mac is in there too? If you build a self contained package using Mono (embed the runtime in the App Bundle) they want you to pay for that now. Even though this has about zero to do with static linking.... I had a 10 minute long argument with a Xamerin representative about how retarded this was, as people have been embedding the Mono Runtime in their Mac apps for quite a long time now. But no, apparently we now pay for that.
I was on the Monotouch Beta and it looked so good. It's a pity the initial pricing was so absurd and even all these years later, it is still impossible to build an app for iOS with the Mono framework without a fee on top of the Apple Developer license. This is why I stuck with Objective-C.
Mono is the framework (like .Net) and Xamarin is the tooling (like Visual Studio). Framework is free (essentially) and the tooling is like VS (starter is free, pro is not so free but has more tools)
Mono has a lot of GPL code. Xamarin has a license to impart commercial licenses to their customers. So Xamarin customers are fine. Mono users will have to abide by the GPL'd bits.
Xamarin For Android and iOS only have "crazy" licensing fees IF you want the professional editions... The Starter edition is free, and their Indie edition is $25 per month: https://store.xamarin.com/.
Yeah, the pricing improved - but essentially, it is impossible to create the same exe for iOS using the open sourced Mono version because of the way in which the runtime is licensed (strict LGPL.) No static linking, so one must buy a commercial Mono license, which would not be the case for this solution.
Are you confusing Mono for Xamarin?