Attachmate has no obligation to do anything. They could just discontinue MonoTouch, Mono for Android, etc, and all existing customers would be left up shit creek without a paddle.

So the fact that they have signed an agreement that gives Xamarin a perpetual license to all the intellectual property of Mono, MonoTouch, Mono for Android, Mono for Visual Studio, etc, is fantastic for any existing customers which use these products.

This outcome is the best possible outcome given the circumstances.